I read somewhere yesterday (at the MagicBox, I think, though I rarely visit that site anymore) that at least 200 PS2 games do not currently work on the PS3.
That may change with updates, but it's very likely that the Wii will have the best backwards compatibility. Very similar guts as the GameCube, after all. I thought the PS3 would have the PS2's insides tacked in, but apparently not, or if they did, they didn't do a good job if 200 games don't work. I wonder if that 200 includes any of the popular PS2 games, or if that 200 is only of generic crap? I suppose it's not a big deal if it's the generic stuff that got left out, but 200 still sounds like a lot that it's still not good news for them.