The third WordPress community summit will be right before WordCamp US in Philadelphia, December 2nd and 3rd. This is the second time the event has coincided with WordCamp SF/US, and the third time it's taking place in the United States.
I'm sure many folks will be disappointed to see the event in the US again; and I would not at all be surprised to see the next one take place at WCEU either next year or the one after that.
The community summits so far have been positive experiences with a lot of good in-person communication, and debatable amounts of follow-up and physical progress. I think they've been great, but I wonder if more structure will be applied this time to help the various working groups hit the ground running when they get home. To be fair, I do think follow-up was better after the second summit than the first.
Now that the full WCUS itinerary is set, it's a good time to start buying plane tickets if you plan to attend. But note that the summit is invite only, so if you aren't a regular contributor to a particular component or feature plugin then be sure to confirm that you'll have a spot.