Source: Facebook.

It's been a good week for social-media giant Facebook (META 0.11%).

Last Thursday, over 1 billion people accessed its service in a single 24-hour period. That's a mind-boggling amount of activity, especially for a company that reported only 1.49 billion  monthly active users, or MAUs, during its most recent earnings report. This level of user engagement, especially for a service showing signs of slowing growth in select mature markets, bears celebrating in its own right.

However, Facebook also made another important strategic move with the public launch of its M personal assistant within its Messenger app last week. While the media largely frames this as a possible challenger to existing personal digital assistants, Facebook's new product actually places rival Google (GOOG 0.92%) (GOOGL 0.93%) squarely in its crosshairs. Here's why.

Meet M
According to its mobile chief, David Marcus, Facebook began testing M among a small number of Messenger users in the San Francisco Bay area last week. Despite the modest beta release, Facebook harbors grander ambitions for M over the long term.

What differentiates M from other digital assistants such as Google Now, and Microsoft's Cortana is its unique mix of machine and human intelligence. According to an interview Marcus granted to Wired, Facebook designed M to not only provide relevant information for users but to also enable them to more quickly achieve the end use of that information. For example, Marcus claims M can help you not only search for information on a possible birthday gift for your girlfriend, but it can also help you purchase the item.  

According to Marcus, M does so by connecting its advanced artificial-intelligence software with real Facebook employees, called "M trainers," who are tasked with ensuring that every request gets resolved in a satisfactory manner. Other mobile on-demand services such as TaskRabbit employ similar man-and-machine models, and M certainly seems useful to an extent, although the degree to which this idea scales also isn't clear.

Either way, Facebook's true intention with M will become clear soon enough. Rather than taking on personal assistants, with M, Facebook might finally be attempting to disrupt the one company many predicted that only it could -- Google.

Source: Facebook.

Facebook's (very) long-term vision
With its unique access to troves of data points -- including pictures and posts, among other things -- and how they relate to one another, Facebook also has the ability to index information at a scale some believe might even exceed Google's comprehensive Web indexing capabilities.  These data points form the basis of Facebook's Social Graph, the informational bedrock on which many have argued that Facebook will create its own search business as a direct competitor to Google. And here, M appears to be the first tangible manifestation of Facebook's machine-learning efforts.

In discussing its long-term strategic vision last year on a conference call, CEO Mark Zuckerberg mentioned Facebook's planning efforts as divided into three-, five-, and 10-year tracks, with Graph Search looming large in Facebook's decade-long plans. In the Wired interview, author Jessi Hempel describes using M, which also roughly approximates how and why users turn to search engines like Google's:

Right now, if I'm looking to treat my summer cold, and I'm in front of my laptop, I begin by googling "cold meds Upper West Side." On mobile, however, I may pull up any number of apps -- Google, Google Maps, Twitter -- to find that out, or I may just ask Siri. ... Marcus hopes to make up for that by creating a virtual assistant so powerful, it's the first stop for anyone looking to do or buy anything.

And as we've seen with Google's massive search-ad profit center, there's a significant economic opportunity here for Facebook as well. In the interview, Marcus goes on to sketch out a possible business model for monetizing M that sounds eerily familiar to the way that Google makes its massive profits: "We start capturing all of your intent for the things you want to do. ... Intent often leads to buying something, or to a transaction, and that's an opportunity for us to [make money] over time." This, in loose terms, is how a search engine operates and generates revenue.

It may be too soon to see M as a key component of Facebook's multi-decade strategy, but in looking at how Facebook's executives discuss M, it becomes clear that the company harbors grander ambitions than simply creating a leading digital personal assistant. So while M is could be seen as just another high-visibility personal-assistant alternative, Facebook's big-picture aspirations appear to present a material threat to Google's search dominance.