This is, apparently, big news from the Facebook blog:
I’m not quite sure what the big draw is supposed to be. How is it different from the existing mobile friendly m.facebook.com site? Its claim to fame is that it is faster because photos need an extra click to view. This removes the process of downloading and rendering them on the top level.
In any case, the site is locked to participating operators. AT&T is not one of them as you can see from my screenshot above. No loss.