Check out this post from Literaticat if you're in the San Francisco area. Her bookstore, Books Inc, is having writing workshops with Rosemary Graham (Thou SHalt Not Dump the Skater Dude, etc.) and readings from Louis Sachar, Jonathan Straud, Michelle Jaffe, Cecil Castelluci, Scott Westerfeld and Justine Larbelastier.

And if you don't know who those guys are, you really need to catch up on your reading.