Before anyone says it, NO, it's not promising Christmas delivery! I've just ordered and it says it's likely to be despatched 5th Jan. But if you want it for that New Year's fitness resolution then it's a pretty good price for what's supposed to be a brilliant game, and sounds like tons better fun than Wii Fit!
People are selling these for up to £70 on Fleabay!
Also avail at Tesco entertainment for a couple of quid more, with 4-5 day delivery if you don't need it by Christmas but want it slightly sooner.