Here's a map (PDF) of the planned Hubway station locations in Cambridge: http://www.cambridgema.gov/CDD/Tran.../Transportation/Bike/BikeShareSites11x17.ashx. Looks like there are 22 of them on that map, so they must not have figured out a couple of them yet. Most places that aren't Harvard or one of the main squares aren't covered too well, but at least there's one near my home!
Quick screenshot of the part of the map that has any stations:
Quick screenshot of the part of the map that has any stations: