According to several Android news sites, Facebook sent out event invitations to several tech sites for a "Mobile Event" at Facebook Headquarters. Rumors are circulating about what the event could be about, with the possibility of a Facebook phone and/or an update to the Android Facebook application or the Facebook site are major candidates.
Back in September, we heard rumors that a Facebook phone running Android was in development. At the time (and to this day, from what I understand), there was no real tangible evidence to back up the Facebook Android phone claim (at least in my opinion.) In fact, Facebook apparently made a statement denying that they were developing a phone.
However, that doesn't mean that Facebook wasn't trying to throw the media hounds off their trail for another two months. Phandroid makes a compelling case for the possibility of a Facebook Android phone
So what else could Facebook be inviting journalists to their headquarters for? Possibilities being rumored include a revamp of the mobile site itself, a revamp of the app to coincide with the announcement/release of Android Gingerbread, the unveiling of the Nexus Two, or possibly the integration of technology from some of their recent acquisitions.
On a personal note, I don't think the Nexus Two announcement possibility is worth having any faith in.
Image from Android Central