Again the X48 is just an X38 with official support for the 1600MHz bus used by the QX9770. Otherwise it isn't any different. The Rampage Extreme and Formula are just like the Maximus Extreme and Formula boards except that they use a slightly different BIOS and the X48 north bridge chip in place of the X38 north bridge chip. So X48 isn't really all that exciting because it is just X38 re-hashed. You'd think that since the X48 chips are speed binned that they'd be better overclockers. My experience however finds that to be untrue. I've seen at least one X48 board that didn't overclock as well as its' X38 counterpart did. Though if you think about it virtually every X38 board can already do 1600MHz FSB (400x4) very easily. So really I doubt Intel is really even speed binning them. I think they just have sufficient confidence that they can officially sanction 1600MHz FSB speeds on that silicon.
So I suppose we won't be seeing a Rampage Formula review then.