Zac Efron ZacVanessaCast.jpgThe third High School Musical - wow, does it really deserve THREE installments? - will indeed star Zac Efron and his scandalous "girlfriend" Vanessa Hudgens, sources tell Us. While a Disney spokesperson says "the cast is still in negotiations" and Hudgens' rep claims "there is no deal yet," the Us source says Vanessa will even receive a "substantial [pay] increase." Whaaaaat! How'd that happen? If she's getting a little more money, Zac should be getting WAY more!