My son will be taking 2 2-week teen theater classes this summer:
There are, I believe, still slots in the teen conservatory but the Hunger Games production already has a waitlist. The teen conservatory supposedly gets a few students from around the country, but most are local.
I believe that all the other summer programs of West Performing Arts still have some space, though a few are on final call (only one or two slots left). There are programs for kids as young as age 4 and others for up to age 21. Here are their programs for this summer:
Summer Classes 2012 | West End Studio Theatre – Santa Cruz, CA.
My son has been working with the teachers in this group for 9 years (he had 4 minor roles in Wizard of Oz with Terri Steinmann directing in July 2004) and has done at least 28 courses with them, all but one of which had a performance at the end (a theater tech class had no performance). Some classes, like the Dinosaur Prom improv troupe, have had more than one show.
I highly recommend WEST for teaching acting to kids, and their teen shows are worth going to just for the entertainment.