Here is another upcoming activity I chanced upon:
The Chinatown Merchants Association will present the 17th Annual Celebration of the City's Autumn Moon Festival the weekend of September 6-7, 2008, from 11am to 6pm each day. During the Moon Festival, Chinatown's historic Grant Avenue will become a pedestrian-only bazaar with live entertainment between California and Broadway, as will Pacific Street between Stockton and Kearny streets. Admission is absolutely free and everyone is welcome.
http://www.moonfestival.org/