Y'see, I don't see much point in having a free company lunch if you're in SF and presumably within walking distance of a dozen good lunch places.
If you're stuck in Mountain View at the Googleplex, though, free lunch is a great idea.
I've worked out of a few different places in SOMA now. There often aren't that many good places nearby. Even if there are a few, you get tired of them. At ZeroCater, we have dozens of restaurants, we add more frequently, and they're all highly rated.
All the cool kids are doing it. (Justin.tv, Scribd, Xobni, Heroku...)