There is no keyboard and mouse support.
But keep in mind that this game plays very differently from other shooters. It has a much more realistic feel to it, and as a result is much slower and easier to handle with dual analogs.
I come from a PC gaming background (just check my game collection), and this is the first console shooter I've really been able to get into (aside from Goldeneye when I was much younger). I've been addicted to the multiplayer beta over the past few weeks, whereas I've played Resistance 1/2 and Warhawk online for a grand total of 20 hours combined, if that. And I've had Resistance since launch!
Killzone 2 feels perfect with dual analog controls, and I actually think PC controls would only hinder the game. It would completely destroy what Guerrilla is trying to do with game.