The Premise: Some kind of heist set up, a la Ocean's 11 or Mission Impossible or The Sting. Not really No Myth, but there'll be plenty of space for ad-libbing as you do prep work, and in-game there may be some retroactive explanation of preparation you turned out to have done. There's probably room for three or four capers in a four or five hour game, although come to think of it, this might work well done in concert with a web forum (yeah, I know, Iain's immediately lost interest). See this livejournal entry for more of this sort of idea.
The Time and Players: Not scheduled or signed up for yet. Maybe in mid-May or mid-June.
The Rules: I'm not sure yet. Something both crunchy and flexible, that rewards specialization and allows for zooming in on detail. Maybe that DitV-ish FUDGE system with the resolution track I have been poking at. It's often the cases that the crooks have some character flaw or background issue that trips them up at some points, and some system that models that would be good.
The Characters: I've been getting into a groove recently of just making the characters for one-shots, but I could conceivably give people more freedom for this, since heist gangs are traditionally kind of a ragtag bunch. Maybe the character roles would be fixed (acrobat, safecracker, hacker) and people would design characters around that.