Just a little one.  Nothing too unusual for California.  The house shook for maybe 30 seconds.  Nothing fell off the shelves.  It's too recent even for USGS to register, so I'll get back to you on the magnitude later.  Could be a small one nearby, or a big one far away.  We'll see.

For flisters around SF Bay, who felt it and how strong was it?

ETA: It was a 5.6 centered 7 miles east of Milpitas on the southern end of the Hayward fault.  It's actually the largest one I've felt in the last couple of years, but not the biggest I've had ever.  The biggest quake I've experienced was a 7.4 in Costa Rica in 1991 which raised the coast line by 2m (6ft).