Sprint is working hard to roll out its 4G LTE network as fast as it can. Although the wireless carrier hasn't made any official announcements regarding LTE availability in the Bay Area Peninsula, users have already reported LTE connectivity around Palo Alto and Mountain View. In early July, rumors suggested the San Francisco Bay market would be one of the next places to get LTE service from Sprint.
Using Speedtest.net, one user near the area was able to obtain download speeds of 13Mbps and upload speeds of 8Mbps. Users have also had luck connecting to LTE in Sunnyvale and Cupertino. Since Sprint hasn't made any official announcements yet, it's possible this connectivity is part of a test phase that could be disconnected before Sprint officially releases the service. Nonetheless, if you're in the Bay Area, it never hurts to see if you can get a LTE connection.
Sprint currently offers 4G LTE service in Atlanta, Dallas/Fort Worth, Houston, Kansas City, San Antonio, and Waco. The carrier has promised additional markets will be launching in the coming months.