On December 2, CNN Money, citing “a source close to Gowalla,” reported that Facebook had acquired the location-based service, which was launched as a rival to Foursquare. Most of the Gowalla team is expected to move from Austin, TX, to Palo Alto, California, where Facebook is based. Gowalla declined to comment at the time, since it has a policy against commenting on “rumors and speculation,” but Foursquare found the acquisition believable enough to have issued a statement of congratulation to its onetime rival. (Foursquare has a half-million daily active users against Gowalla’s 10,000, reportedly.) Then, on the 5^th, it became more than mere “rumors and speculation,” with Gowalla co-founder Josh Williams confirming the deal on the company blog.

At first blush, it seems an odd acquisition. After all, Facebook itself already allows you to check-in and share your location with friends. In some respects, Facebook may simply be using the acquisition as a technique to pilfer visionary programming talent, as it has done before with other companies (Snaptu, for instance, or Hot Potato). In the way some companies acquire others as an IP play, Facebook may be doing so simply as a human resources play: attracting top talent. Some term this an “acq-hire.”

But one of the most intriguing details that emerged in the sparse CNN Money report was this: that the Gowalla team would be working directly on Facebook’s Timeline feature, which though announced some time ago and expected for release last month, has fallen behind schedule.

Viewed in this light, the Gowalla acquisition shows that Facebook has ambitions not only to expand in time (being a record of your past), but also in space (being a record of all the places you’ve been). Gowalla refers to their product as a “passport”; and Facebook’s acquisition of Gowalla points to Facebook’s own ambitions to be something like the central passport authority on the web.

Recently, the author Salman Rushdie got in a fight with Facebook, which insisted that he use the name Ahmed Rushdie online, since that was his legal name. (Rushdie eventually prevailed.) The New York Times pointed out how the debate shined a spotlight on Facebook’s stance on the so-called “nym wars.” In brief, Facebook has a large stake in having people use their real names on the web; wrote the Times: “One side envisions a system in which you use a sort of digital passport, bearing your real name and issued by a company like Facebook, to travel across the Internet… [Facebook] is becoming a de facto passport vendor of sorts, allowing its users to sign into seven million other sites and applications with their Facebook user names and passwords.”

The Gowalla acquisition points ahead to an era–perhaps one in which we’ve already half-arrived–where Facebook is something like the Internet’s own State Department: the authority governing your travel throughout the web. For members of the next generation, Facebook may be more than a mere aspect of their digital lives, a website they may check occasionally. It may become as inseparable from their online identities as their passports, birth certificates, and social security cards are from their offline ones.