Theatre of the Imagination does "High School Musical" Parties........costumes, music, production and DVD of the show all included. You could put out the red carpet and give out awards, serve popcorn, etc...
Go all out and rent a limo and drive around and be "movie stars" for a night. I did the limo after having a libby lu party last year and the girls LOVED it. We went through the McDonalds drive-thru and then drove to the plaza and back.
Let me know if you would like their contact info. Miles is the director of the Theatre. I believe the party is an 1 1/2 long and runs $200.
Even if you didn't use Theatre of the Imagination.......you could always use the theme. Go to Disney.com and search for High School Musical and they have party ideas on there also.
Feel free to contact me for more ideas.....(I kinda do "party planning" for all my friends and have a ton of ideas!)