Well, so far it's known that:
- the writers have already gone back to work
- the cast come back on set in a couple of weeks, July the 9th, to be specific
- Ed Bernero asked the fans (via Criminal Minds Fanatic Blog) who of the characters we'd like to get more backstory on and promised to make that happen in one of the first 5 episodes. According to poll results it's gonna be Hotch. :)

That's about it so far. :)

sorry I don't but it should be good.