Originally Posted by fsa3
I guess my question was whether or not how google was doing this was using public information - seems like it's not. That sure would have been cool.
My understanding is that Google harvested data from Google Maps users who had GPS and then mapped that to cell tower information. That is, they took the info from the BlackBerry API (e.g. GPRSInfo class) and uploaded that to their servers with a reading from the GPS. When they had enough data, they had the non-GPS users just download a location based on the cell info.
So to reproduce this, you'll need to buy a list from someone, ask Google to open their API, or get enough users to harvest the data that Google did. You can do some amazing things with a massive user base.