I think the lively chess scene at 5th and Market was shut down as a public nuisance. As far as I know it has not reappeared. At least it wasn't there the last time I was in San Francisco in February.
There is always Xiangqi going on in Portsmouth Square in Chinatown. But that's not exactly what you are asking for, I know.
A beautiful outdoor venue is Santana Row in San Jose. (Not exactly close to San Francisco, true.) Evenings and Saturday are the best times, but you can't always count on finding an opponent. You can find out what a great chess environment this is by googling YouTube for some videos. Chess.com has had meetups here. It's not too far from chess.com world headquarters.
I don't know anything about the Berkeley scene.
Amy
I'm in the bay area CA for the summer. Does anyone know of a park/outdoor area where people play chess in San Francisco or Berkeley? And what day/time is good to go? Thanks!