I was outright and asked at the interviews I went to, when was the decision going to be made. Many of them said "we wouldn't have invited you if we weren't going to give you an offer". It appears that references and your CV seem to give the best impression. However one university, I sent an email the day after my interview, thanking them for my day, and they said that a decision had been made and the offer was being processed.
Just send an email if you don't hear anything.