Dead Rising 2 and a PS2 Wiimote, the most credible rumor is that God of War: Chains of Olympus may be heading to PS2. EGM's resident man of mystery writes that Chains of Olympus may head to the PS2 later down the line, sometime after its release on PSP. It's worth wondering how much of this is rumor reporting, as opposed to "common expectation" at this point.
Many high-profile PSP games have made the jump to PS2 in recent years, and GoW: Chains of Olympus could certainly fit that category. Just recently, Silent Hill Origins and Ratchet and Clank: Size Matters made the leap from portable to big screen. We'll be sure to welcome Kratos from a safe distance if he ever decides to make the jump.