According to a recently published interview by Gamasutra with Sony Online Entertainment producer Todd Carson, the puzzler on wheels title GripShift and Cash Guns Chaos would probably be the only titles originally conceptualized for the PSP to be released on the PlayStation 3. Quoting Carson, he said, "Not at this time."

You buy games on the PSP because it’s a mobile device, you want to take it on the run. The two consoles really are two separate entities - and while people might have both and buy [GripShift] on both, we didn’t see them necessarily as competing with each other.

The other thing that actually helped influence our decision [to focus on the PS3 first] for Cash Guns Chaos is that you really need to play the game with two analog sticks. While the PSP has one analog stick, we had set up controls where you had to use the X, circle, square and triangle key to control which direction your character was shooting.