I was wondering whether we may get a modified form factor for the iMac at MWSF, since it'll be one year since it went Intel. Apple wanted to keep the form factor the same during the Intel migration to reinforce that it was the same machine, but with that now over anything's possible.
I still think it'll be C2D based though. Probably with a few enhancements such as a Blu-Ray option and better graphics.
Up to you really, although the 24" iMac would win me over if I were in your position.