I'll attempt to keep this list updated, since the only thing less useful than an obsolete list of upcoming appearances is an obsolete list of upcoming books. (Actually, that one's more useful -- at least you can still go find the books.)
March 21-25, International Conference on the Fantastic in the Arts, Orlando, FL
March 30-April 1, FOGcon, San Francisco, CA
May 19th, SF in SF, San Francisco, CA
June 22-24, Fourth Street Fantasy, Minneapolis, MN
August 3-6, Mythcon, Berkeley, CA
October 11-14, Sirens Conference, outside Portland, OR
November 1-4, World Fantasy Convention, Toronto, Canada