The first downloadable Penny Arcade adventure is coming soon to Xbox Live Arcade, Mac, Linux and PC. Why is it not coming out on PSN? Simple: the Torque Game Engine isn't compatible with the PS3, at least not yet. It was always intended to bring the game over to PS3, explained a representative from Hot Head Games. However, the engine's lack of support for Sony's console made it impossible to make it multiplatform.
The Torque Game Engine is commonly used for Xbox Live Arcade games because it is a low-cost solution for developers that can't invest in other options, such as the Unreal Engine. Downloadable titles need to keep their costs low, especially when developed by independent teams. For now, it seems as though Penny Arcade Adventures won't find a home on the PS3.