Will castle crashers be on the PS2

I wouldn't hold my breath for the PS2 release. Castle Crashers is developed by a small team (The Behemoth), and they have to budget how they use their time. They've previously stated that they would like everyone who wants to play their games to be able to enjoy them, but they will of course pursue the paths that generate the most revenue for them.

They've recently decided to release it for the PS3, though, no release date has been set. I would expect sometime around August 27th, though.