It wasn't long after Yammer moved up from LA that I joined, so IMHO it was a good move :) SOMA is just about the perfect place for startups: tons of converted office space, access to both City and peninsula engineers, it's easy to get to, and technology permeates almost everything you do.<p>The only real drawbacks are the cost of living and that we're in an echo chamber (SOMA) that's inside an echo chamber (Bay Area); it can be hard to remember that Uncle Joe doesn't check in on FourSquare, has never bought a coffee with Square and doesn't know who @aplusk is. Some startups <i>really</i> lose that perspective. I've worked at some of them. Yammer has perspective, a business plan, and Sacks and our CTO are the best leadership I've ever worked for. If we stay on our current trajectory, someday we'll graduate to needing a campus office park in Palo Alto. But for now, SOMA's a great place to work.
Interesting, but seems hardly surprising - also not restricted to San Francisco. Where I live (Europe) the trendier and younger companies are in warehouse-style offices in the inner city and the more established ones have moved into bigger, more purpose-built places in the suburbs because they need the space and their workforce wants to live there.