Gamescom could be it. I expect something from GG and MM there. Will be sweet. Oh, and also Quantic Dream (but they might be at E3 too)
Well Tidux claims it's going to be revealed at E3 so we'll see. He actually didn't say anything about MM when he was referring to what he knew about the supposed leaked E3 Sony plans. So it's possible, perhaps even likely, that Sony will wait until Gamescom to show show off Media Molecule's new IP. I'm also expecting that to be when they show any games London Studio is working on and Singularity from Quantic Dream.