although I am not an annoying Fanboy, I have to say nothing has really made me want to buy the PS3, sure Killzone and resistance look great, but considering thats it right now, its not enough, and I don't need it to play my PS2 games, as I still have my PS2 from when it was released.
for now I'll stick with my 360 mainly for convenience, most of the games coming on PS3 are also on 360, and some exclusive ones too (bioshock, Halo etc)