Where are app stores going next? For the past few years, the app store model has spread through the wireless ecosystem like wildfire. There have been a few big winners and lots of ... well, losers is probably too strong, but let's say there are a lot of app stores that have yet to reach critical mass.

App stores can be measured by the three Ds: Distribution, Developers, and Downloads. How many devices have the store, how many developers are building apps for the store, and how many consumers are getting enough value to actually download something from the store? This is what makes it so hard to break in -- it's an outrageous amount of work (and marketing) to line up distribution and developers so that you can get a critical mass of downloads.

Yesterday in San Francisco, Intel threw its hat into the ring. Building on its announcements at the annual Intel Developer Conference, Intel announced the full release of its "AppUp Platform" -- a new app store for notebooks and mobile devices. AppUp is a storefront that's neither hardware nor OS dependent. Although it is being launched for Windows, it will support the MeeGo Linux platform (developed jointly with Nokia) when it launches, and it will be available across netbooks, phones, and a forthcoming zoo of in-between devices. It supports a variety of runtimes -- Adobe AIR and C++/Win32 natively, with wrappers available to enable Silverlight, .NET, and more. [Editor's note: The author contributed content to the AppUp conference.]

But Intel's (Nasdaq: INTC) first target is the massive installed base of netbooks, estimated to be over 100 million strong. Conference attendees were quick to ask, "Why netbooks?" Intel answered with projections of over 500 million devices that would be capable of utilizing the AppUp platform within five years. That's a huge revenue potential that would dwarf what Apple (Nasdaq: AAPL) and Google (Nasdaq: GOOG) have been projecting for their respective platforms.

And Intel wasn't ignoring the app store out of Cupertino, either. Demos at the session highlighted a simplified process to get iOS apps running in the AppUp store. That has to be tempting to Apple developers -- an ability to leverage their development investments across a much larger market.

A fascinating development along with the AppUp launch is that Intel is welcoming alternative storefronts. That means a company can create a custom user interface with all or some of the AppUp apps, using Intel for transaction fulfillment. Adobe, for example, is launching the Adobe AIR Marketplace -- a storefront that highlights AIR apps (and only AIR apps) in the AppUp marketplace. They decide what to carry and what to highlight; Intel handles the dirty work. Intel even allows "shopkeepers" to charge app vendors for premium placement and collects the proceeds on their behalf.

Does the world need another app store? It's tough to say. On the one hand, it will be a nightmare of marketing for Intel to get mindshare amid a sea of alternatives. On the other, I would be loath to bet against Intel's marketing muscle -- and they are targeting a massive market with a unique value proposition.

Will they nail the three Ds? I don't know, but I'm looking forward to finding out.

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Dan Shapiro is the co-founder and former CEO of Ontela (now Photobucket). He serves on the boards of Photobucket, Bonanzle, and the Washington Technology Industry Association.