Just got pinged about this from Jonathan. From the WSJ (sub required):
Yesterday Facebook's new mobile services were made available to students at three colleges -- Harvard University, Stanford University and the University of California at Berkeley. They will be available to students at more than 2,000 universities by the end of this month and high-school users of Facebook by early May, company officials say.
Any phones with text-messaging capabilities can support the new Facebook services; students don't have to download special software or pay extra, though they may pay more total fees for data usage if they send more text messages.
Facebook also has moved its popular "poking" application to phones: Users "poke" others on Facebook by sending quick, blank messages -- recipients get a notification that says "you've been poked" -- that indicates someone is thinking about them. In addition, students can now use their phones to locate phone numbers or email addresses of other Facebook users; they send a text message to the address "fbook," a centralized directory that looks up the name. (Facebook users can use privacy controls to limit those who can access phone numbers and other identifying information.)
Interesting - they decided to go with Text Messaging rather than something more elaborate like MySpace is doing with Helio. I'm on board with that, actually. I'm sure they have rev-share deals with the operators as well, so it could be a profitable business for them. (Maybe they are worth $2 billion! ;-) ).