One of the most persistent criticisms of Facebook is that it's trying to build a "walled garden" analogous to AOL's dialup service in the 1980s and early 1990s. Blogger Jason Kottke said it in 2007. Tim Berners-Lee said it in Scientific American in 2010. Google's (Nasdaq: GOOG) Vint Cerf revived the meme earlier this week at an event organized by the U.K.'s Guardian newspaper: "You can't stay locked into a closed environment for very long before people will start demanding that it open up so that it becomes more interoperable with everything else," Cerf said.

The tech blog VentureBeat repeated the hoary accusation in a Sept. 20 article about The Wall Street Journal's new Facebook app, which highlights the articles your friends are reading. "New Walled Garden," VentureBeat labeled the WSJ app, presumably because it lets users read articles from the newspaper from within Facebook, without ever going to the WSJ website. The delicious irony here is that VentureBeat's article begins with a prominent Facebook "Like" button (it has more real estate than the Google +1, LinkedIn (NYSE: LNKD), and Twitter buttons combined) and ends with a Facebook social plugin showing thumbnail images of Facebook users who've "liked" VentureBeat. If Facebook is a walled garden, there sure are a lot of players on the Web that want to get in.

But the truth is that the walled-garden trope was never very accurate: Facebook is a child of the open Web, and the company focuses on HTML-based delivery technologies almost to the exclusion of alternatives such as native mobile apps. And with this week's announcements at f8, Facebook's annual developer conference in San Francisco, the charge that Facebook is a closed environment rings even less true.

Forget about "Timeline," the redesigned Facebook profile format that everyone is buzzing about; it's pretty, I like it, and I'll have more to say about it later, but the real news at f8 was about the coming expansion of what Facebook calls the Open Graph. This overhaul isn't simply going to change how people spend time inside Facebook; it's going to make it easier to find and share information across the digital universe. The changes will cement Facebook's role as the default social fabric weaving together everything else on the Internet. And I think they herald an important redistribution of power within the triumvirate of Silicon Valley companies -- Google, Apple (Nasdaq: AAPL), and Facebook -- that currently dominate many people's digital lives.

Open Graph is the protocol that makes outside Web pages recognizable to Facebook's infrastructure. When you click on a "Like" button at VentureBeat, Xconomy, or thousands of other sites, you're using Open Graph to tell Facebook that it's OK to publish updates about that site on your profile. Facebook said yesterday that it's handing developers the ability to define new Open Graph actions and objects, which means the range of updates that sites and apps can send to Facebook is about to get a lot broader.

To quote from Facebook CEO Mark Zuckerberg's f8 keynote talk:

Facebook's mission is to make the world more open and connected. We do this by mapping out all of the things you are connected to. … As a first step toward this we made it so you could connect to things by Liking them. … This year we are taking the next step, so that you can connect to anything you want in any way you want. Now you don't have to Like a book, you can just Read a book. You don't have to Like a movie, you can just Watch a movie. You can Eat a meal, Hike a trail, Listen to a song, and connect to anything in any way you want. This will let you make an order of magnitude more connections than before. We are helping to define a new language for people to connect.

Facebook is taking this "new language" idea quite literally. As Zuckerberg explained, the first iteration of Open Graph allowed lots of subjects and objects, but only one verb: Like. Now it's letting outside developers add lots of new actions: "Mark reviewed a restaurant." "Mark completed a 6.5 mile run." "Mark listened to '21 Guns' by Green Day." By dropping the right code into their website, Facebook apps, or mobile apps, developers can now cause almost any action to be published to their users' Facebook profiles. And thanks to some additional changes, these sites and apps won't have to bug you over and over again about whether you really want to share something on Facebook; once you've authorized the connection, tidbits about your activities will be published automatically.

Each update that lands on a Facebook profile will include links that let that people's friends investigate further, or pursue the same experience for themselves. If you share the fact that you listened to "21 Guns" using the new Spotify app on Facebook, for instance, then your friends will be able to listen, too, right this instant. (Some updates will show up in your timeline or news feed, but to minimize the clutter, Facebook is moving many of them into a new area called the Ticker, which Zuckerberg called "a socially acceptable way to express lightweight activity.")

The "Like" button spread across the Web so quickly that it's easy to forget that Facebook introduced it only 17 months ago. But if you thought that was fast, watch out for the new "Add to Timeline" buttons that will start appearing in pages and apps everywhere. Open Graph already represents a huge, basically zero-cost opportunity for word-of-mouth sharing and discovery, and now that Facebook is giving media companies, game publishers, and other content creators and distributors more tools for controlling how their products are represented inside Facebook, it would be dumb not to join the party.

Far from being a walled garden, Facebook is evolving into a real-time communal blog, where everyone with an Internet connection can share virtually everything about what they're doing, creating, and consuming. To Facebook's credit, it's not trying to centralize or tax all this activity the way, say, Apple is. It will profit, of course; the more information users share about their preferences and activities, the more Facebook can charge for precisely targeted advertisements. But the sharing that happens through the Open Graph will spawn plenty of new outgoing traffic, as Facebook users act on all the implicit recommendations they're finding in their friends' updates -- Zuckerberg called this "real-time serendipity."

And that's how the changes in Open Graph will redraw the playing field where Facebook, Google, and Apple -- and, of course, a collection of second-tier social players like Amazon.com (Nasdaq: AMZN), Microsoft, and Yahoo! -- are vying for our attention and our dollars. I don't buy the argument some commentators have been making that Facebook is trying to build a Web-based app platform to rival Apple's iOS or Google's Android; Facebook is a social hub first and foremost and will never be a vertically integrated hardware-software-content player like Apple. But I do think Facebook is demonstrating that it has a better understanding of the way people actually find content than either Apple or Google.

As impressed as I am with Google's come-from-behind effort in social networking, there aren't many signs yet that the search company sees Google+ as a hub for media discovery or social commerce. And on the mobile front, the app-store model created by Google and Apple is in huge need of Facebook's social touch. I love my iPad and iPhone, and mobile apps are absolutely the hottest area for consumer technology innovation right now. But let's be honest: The app-store experience sucks. With half a million apps to choose from in the iTunes App Store and the Android Marketplace, consumers can't find what they want and developers can't get noticed.

Through their featured-app and hall-of-fame lists, Apple and Google make meager attempts at curation, and startups like Chomp are working on search-based alternatives. But my prediction is that Open Graph will become one of the main conduits for app discovery. You can bet that mobile developers are already shaking off their post-f8-party hangovers today and figuring where to put the "Add to Timeline" buttons in their apps, and what kinds of deeper Facebook integration to attempt. Facebook's argument, articulated at f8 by Chief Technology Officer Bret Taylor, is that the more opportunities for sharing and expression that app developers can give to their users, the faster their apps will spread. "The app that is able to set the expectation that everything is social up front -- that is the app that is going to win," Taylor said. When you have 800 million users, that's a pretty easy case to make.

And we haven't even heard the whole story from Facebook yet. The company said very little at f8 about its strategy for the mobile world: For example, there was no announcement, as I (and many other commentators) had expected, about a new Facebook app for the iPad. It appears that the company didn't want to dilute the message about Open Graph at f8, and plans to wait a few more weeks before talking about mobile initiatives such as its massive Spartan project. That's an effort to use HTML 5 technology to create a version of Facebook that has app-like functionality but runs inside the Safari mobile browser on the iPad, thereby sidestepping Apple's content controls and sales commissions. Once Facebook has made Timeline, Ticker, and all its other improvements accessible from the same mobile devices where people are buying and using apps, the whole cycle of content consumption, social recommendations, and content purchases ought to spin that much faster.

So all that walled-garden talk? If it ever made sense, it's now completely obsolete. I think Jason Kottke was actually somewhat prescient about this in his 2007 post, when he called Facebook "AOL 2.0." Kottke wrote the following: "Eventually, someone will come along and turn Facebook inside-out, so that instead of custom applications running on a platform in a walled garden, applications run on the Internet, out in the open, and people can tie their social network into it if they want." He was exactly right -- but it turns out that the "someone" is Facebook itself.

Wade Roush is Xconomy's chief correspondent and editor of Xconomy San Francisco. You can e-mail him at [email protected] or follow him on Twitter at twitter.com/wroush. You can subscribe to his Google Group and you can follow all Xconomy San Francisco stories at twitter.com/xconomysf.

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