Great!

Unfortunately I'm going on a holiday a few days after the compo starts (Probably 7 or 8 July). I go camping, so I probably can't get online. Getting a design doc ready on time might be a problem. Guess I have to start writing one as soon as the theme is announced.

And what kind of information must this document contain exactly? Alot of technical details also? And to what extent can I drift away from my original plans (This happens quite alot)?

I think the best way to go is to aim low and make some detailed plans. Ofcourse it's also a matter of motivation, which will depend on the theme and my own "gamedev inspiration". I just hope I'll be able to stick with the rest of you guys until the very end.