of the EU PlayStation Community (linked above) has just posted up a huge Q&A session regarding Killzone 2. He confirms that the game will run at 720p at 30fps, there is a public BETA trial coming up, there will be 8 online maps at launch, and HOME will definitely be supported as well as trophies!
To quote: KillZone 2 Q&A
1) Q: What resolution and frame rate does the game run at?
A: 720p at 30fps