TLDR: Come to the city with your A game, couch surf, and go to in-house interviews. Use good job sources, and get a recruiter working for you before you get here.
I'm a 25 year old junior rails developer, and moved to the city 3 weeks ago. I'd have to say the hunt has been humbling. I had assumed the city had tons of companies starving for work, and so I aimed at some of the big guys. Pivotal, Square, Twitter, Yammer, Airbnb and many others.
I've come to the conclusion, Companies have quite the pick when it comes to Quality geeks in the bay area, So be ready to bring your A game.
After week 3, I have some offers on the table, and am beginning weigh my options. But am still actively hunting down jobs that interest me. Other things that could help:
* couch surfing * applying to jobs before you get here (github jobs, or your favorite web companies job page) * get a recruiter working for you - its free for you, and they have alot of sources. granted they don't have your entire best interest, it still gets you interviews.