Yes, ladies, you will be hit on a lot at a conference filled with mostly guys. You are an attractive minority. Now, to the point:
--- There is no excuse for physical assault. I can even almost excuse a guy going in for a peck, but grab-ass and worse are not cool. If you're going to proposition a girl, do it with your wits and your words, not a firm, open palmed slap on the behind.
On behalf of all young, healthy, mate-seeking males, I apologize for the few who make us all out to be classless jerks.
--- Of course, it can be argued that you shouldn't be looking to hook up at a FOSS conference, but really... when ISN'T a single guy looking for a woman with similar interests (inside and outside the bedroom)? This isn't a 'geek' problem, it's a 'human' problem.