We're guessing it's going to be a Fall release. That would put Insomniac on a two-year cycle for this game, which should instantly alleviate any concerns about the game's eventual quality.
Sadly, if the teaser trailer from GamesCom left you clamouring for more... That's your lot for now. Insomniac are bringing their new project to PAX, but it's the Ratchet flavoured one they're showcasing.
We hope to see more of Resistance 3 before the year's out, but we're not holding our breath.