Math Camp 2012 will be happening in St. Louis, July 19 to 22.
Guerrilla Professional Development, organized by and for (high school?) math teachers. Sam Shah and Cheesemonkey are involved in this, so I'm convinced it's gonna be good. I have a feeling the other organizers, Shelli Temple and Lisa Henry, will be familiar names by next year.
I'm going to the Math Circle Institute in early July. If I had more money and more time, I'd go to this Math Camp too.