Since the mid-naughts SF2G has served as a catalyst for cyclists to commute from San Francisco to the Peninsula. The focus has been Google's Mountain View campus, but I've never worked for Google, and I've ridden with the group to Stanford Campus, my old office on California Ave in Palo Alto, and to my present work-place south of Google at the Mountain View - Sunnyvale border. There's no leader; instead riders call rides via the Google Group, then others affirm their intent to join with a Googlesque "+1".
But until now, despite the fact SF-to-Peninsula is considered a "reverse commute" (although with the flight back to cities from suburbia this is changing), there's been no comparable organization of cyclists who work in the city and live on the Peninsula (the "forward commute"). That changed today with the launch of a new group, "Pen2SF". They also have a web site (still under development as I write this).
I really hope it takes off, because the group can serve not only riders working in the city, but also riders who work in the northern peninsula, for example South San Francisco, Foster City, and San Mateo. And people making this "forward commute" have a big advantage: the wind tends to blow lightly from the south in the morning, and strongly from the north in the evening, so at least in the evening commute there's a substantial tailwind likely over at least a portion of the ride.
With the enormous popularity of cycling here, and the favorable weather, there's a huge latent demand. Success is just a matter of people finding out about it.