It's not that they can't pull the information from the towers, it's that the information isn't very good. If you have a real GPS fix and you upload that fix to Google along with the tower, they can start building a very accurate map of where what towers/APs are where. Then when somebody comes along that doesn't have a GPS fix, they can get a better fix than they could otherwise.
Tower-based cell tracking (triangulation based) generally has the precision of several meters if not better. That's more than enough for building very accurate map. Though there's a chance Palm is not allowed to access this information without a warrant, which would explain why they are using alternative collection methods.
I've noticed that of friends with GPS-phones, the tower tracking is always horrendous. Generally it is enough to get you into the right part of the city, but not enough to do any real navigation with.
