Ken just pointed out this recent change to the Bay Area Bike Share FAQ, which now says San Francisco bikes can only be docked in San Francisco stations, while bikes in the other cities can be docked elsewhere (but presumably not in San Francisco?).
The FAQ also notes that riding from, say, San Jose to Sunnyvale might exceed the 30 minute time limit, which means overtime fees.
Bay Area Bike Share announced this FAQ changed a couple of hours ago. I checked on the day of Peter Coljin’s epic 47 mile bike share bike journey from San Francisco to Mountain View and a couple of days after, but didn’t see this text then.