OK! magazine has learned Zac Efron and Vanessa Hudgens have split up. A source says that while Zac was in Europe promoting ‘Hairspray’, his ‘High School Musical 2’ co-star was “all over” her older date at a party in the Hollywood Hills. When someone asked the 18-year old about Zac, she “threw a fit and said ‘don’t mention his name!'” Hudgens’ rep is denying the claim. Read more.