It looks like Colin McRae 2005 won't be coming to the PS2 after all. According to multiple websites, Codemasters' own site is saying the game will be an Xbox exlusive. Here's the quote:

"Anyone who asked me a few months ago if the game was coming out on PS2 in the US, I told yes, because that's what I was told at the time. However, for some reason- (probably retailer/distributor issues) it's now been decided for an xbox-exclusive… sort of.
Sorry for any confusion caused- sometimes people tell me the wrong thing…"