The next JemCon will be SEPTEMBER 24th-26th 2010 in Manchester, NH. The theme is "Set Your Sails for New England." You can get all of the information, including REGISTRATION and CONTEST details here:
http://www.jemcon.org/
I went to the 2008 JemCon and it was a blast. From what I hear it just gets bigger, better and more outrageous every year.