GOW2 is for the PS2, afaik.
Which from my perspective is the right thing to do.
But for must people it is pretty disappointing.
It reminds me a little of Syphon Filter. SF3 was released for the PSOne, when everybody was expecting it for the PS2. When the PS2 iteration of Syphon Filter finally apeared after a long delay, it was pretty disappointing.
I hope that the PS2 continues as a strong platform until 2008. I do not think it is healthy to have such short hardward generations. 4 years is way to short to get the most out of the hardware. I honestly think that Xbox could of handles Kameo, PD0, PGR3 and COD2 with very little difference from the 360 versions. The first three of these are all using modified Xbox engines by the developers own admissions.
If the PS2 had been replaced after it's fourth birthday, we would never have seen stuff like "Black", which is a pretty amazing technical achievement to be running on 6 year old hardware.