Awww.............:] Senior Prom + Graduation.Aviv confirmed that Zac Efron, Vanessa Hudgens, Ashley Tisdale, Lucas Grabeel, Monique Coleman, and Corbin Bleu are all in talks of reprising their roles for a third time.  The original plot, which was to have been titled Haunted High School Musical, was to have centered around spooky happenings at East High. This idea has been scrapped. Although strange things happening will be a side plot, the movie has been rewriten. The new working title has been named "High School Musical 3" and will center around East High's senior prom and graduation of Troy and the gang.
Zac Efron confirmed to Richard and Judy (British talk show) on Wednesday, August 29th, that he, Vanessa Hudgens, Lucas Grabeel and Monique Coleman are all reprising their roles. He does not know about Ashley or Corbin.
Disney Channel Worldwide president of entertainment, Gary Marsh, said of High School Musical 3, "We're working on a script and talking to talent. ... We're hopeful and optimistic we'll pull everybody back together." 
It is reported that Zac Efron, Vanessa Hudgens, and Ashley Tisdale are all refusing to start production until their salaries are raised. Efron has reportedly been offered $2.75 million while the others have been offered $1 million to appear in the movie, set for the big screen next year. Rumors are running rampant that Efron will walk from the movie and, if he does, Hudgens will follow him. An insider reportedly informed the press, "Zac’s telling the other actors to make sure they get what they deserve."