Okay... I am a pretty experienced party animal, and this stuff (sexual assault, that is...not random hookups) is NOT normal. I've heard the occasional story, but both you and the author of this post seems to imply that this is a pretty regular occurrence. Hell, if "it was everyone else's job to prevent being sexually assaulted" and her friends "managed to do this job on several occasions" (parapharasing here), this sounds like one of the seediest parties I have ever heard of. Stuff like this does NOT fly in any normal social setting - the guys usually have the decency to back off before things get too awkward, and if they don't, someone will usually break in and stop it.
I've never been to one of these conferences, but what's the deal here? Being a bit of a cynic in regards to the social skills of a lot of techies, I'm thinking that this is could be the result of alcohol + desperate and socially inept guys + a few women that don't have the critical mass to put up a proper pick-up shield. If this is really a normal phenomenon at tech conferences, I'm a bit shocked that no one have mentioned it before.
The incidents that have been mentioned sound more to me like completely clueless pick-up attempts than any genuine attempt at assault or rape, but the end result is pretty much the same.