Similar situation... what do you guys do/say when people are talking loudly in a quiet study area at the library?
I was on the 5th floor of Mills the other day and these two girls wouldn't stop talking... I just said "Do you mind?!" and they stopped for a couple minutes, then continued on....
THAT infuriates me more so than someone talking during lecture.
Go to the main floor of Mills if you want to talk/do groupwork!!!