Somebody at Ubisoft may have pressed the wrong button early, leaking information on Assassin's Creed: Revelations to the public.
The Facebook update (which has since been hastily removed) included links to an image telling fans to "spread the word," and a Flash file (reportedly, anyway - I can't get it to load myself). Said Flash file supposedly contained the Assassin's Creed: Revelations logo you see here, as well as the name "Altaïr" in Arabic script. Altaïr, of course, was the protagonist of the original Assassin's Creed.
Now, all of this information should be taken with an entire shaker of salt - while the image on Ubisoft's servers does indicate that the publisher is about to reveal information on the next Creed, nothing else is concrete.
Even if we did extrapolate that this game returns players to the Crusades instead of the Renaissance-era Italy of AC2 and Brotherhood, we know nothing else. Revelations (assuming this is the actual name) could be a portable title like Bloodlines, or it could be a full-fledged console title like the three main games in the series. Heck, it could be an iOS or Facebook title too, for all we know.
One thing's for sure, though: If the game really does bring back Altaïr, it shows that nobody likes bland ol' Desmond - not even Ubisoft.