http://www.google.com/support/mobile/bin/answer.py?answer=39...
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Which phones does Google Maps support?
Google Maps works with the following devices:
* Most Java-enabled (J2ME) mobile phones.
* Palm devices with Palm OS 5 and above.
* All color BlackBerry devices.
* Windows Mobile devices with Windows Mobile 2003, 5.0 and above.
* Symbian Series 60 3rd edition devices.
If your device is supported and you have a data plan, visit www.google.com/gmm from a mobile web browser to download Google Maps. If you're not sure if Google Maps will work on your device, visit www.google.com/gmm and we'll perform a quick check to see if your phone is supported.Note: Google Maps doesn't work with BREW-enabled devices. Some mobile services providers may restrict data usage by applications. We recommend contacting your mobile provider to confirm the details of your data plan.
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A company called Navizon ( http://www.navizon.com/ ) has such a product, and they rely on users to wardrive for WiFi and cell towers.
I was just wondering about that. It would really make sense if the GSM/CDMA standards had the tower pass their position to the cellphones, but I guess that was not something the people designing the systems had in mind back in the days.
Finds my position in Finland with ~1 km accuracy, and it is actually quite fun to see where the tower you are connected to is. For me that changes when I change my position in my kitchen...