From Inman News, more about Google Base which has the potential to become another MLS. But to quote Vince Malta, the President of the California Association of Realtors who described it as "Realtor.com lite":
"I represent Cole Valley, a San Francisco neighborhood. But Google Base doesn't break it down to that area. You'd have to search by ZIP code and find yourself in neighborhoods you don't want," Malta said.
Except, Vince, when it does.