Guerrilla last graced the PlayStation Portable with Killzone: Liberation way back in 2006. Since then, the studio has focused on the PS3, but producer Steven ter Heide has stated that it may return to portable games with the PSP successor.
"It’s something we are looking at, but for now our focus remains on the PS3," he said. "We have built up our experience, tools, and engine on that platform. But as with all Sony hardware, we will always keep an eye out and see if there is something we want to be involved with. That’s really one of the benefits of being a first-party studio, early access to all of the new toys!"
Judging from gamer reactions, a new Liberation game would be very welcome. For now, the NGP is getting a full-fledged Killzone FPS, one developed by Sony's Studio Cambridge.