Speaking of being fully backwards compatable, the Revolution is going to allow you to play Gamecube, Nintendo 64, Super Nintendo, and the original Nintendo games on it. You would have to download the 64, SNES, and NES games but the Revolution comes with built-in ports that allow you to use GC controlles and memory cards. This looks especially promising for those of you that are old enough to remember the days of the NES and SNES (Chrono Trigger and Final Fantasy III better be downloadable or all hell will break lose.) will find this very pleasing.I pesonally think that the PS3 will have more vaule. It will have a larger selection of games. It's fully backwards compatalble (wtihout emulation), it will play more media types by default without 'upgrades'. And it's the same cost as the Xbox 360! In short, it most likley will have more value for your cost.
I'm more than likely going to treat this like I treated the current generation, stick with Sony and Nintendo. But the Xbox 360 looks to be very promising in my eyes.