Treasure Island is an artificially created island in the San Francisco Bay that is adjacent to Yerba Buena Island, which intersects the Bay Bridge. Treasure Island was formerly home to a naval base, and now is host to a number of residences. It is serviced 24 hours a day by Muni bus 108.
There's a number of large warehouses on Treasure Island, and movies are routinely filmed there (such as What Dreams May Come).
In 2007, the island emerged from a ten-year, post Cold War slumber to host the Treasure Island Music Festival, attended by 10,000 and headlined by Modest Mouse and Thievery Corporation.
References: 09-12-07, SF Weekly, Gimme Indie Rock, http://www.sfweekly.com/2007-09-12/news/gimme-indie-rock/ 09-17-07, SF Weekly, LastNight: Modest Mouse ..., http://blogs.sfweekly.com/shookdown/2007/09/lastnight_modest_mouse_spoon_a.php