Navizon, which just showed up in Installer, is an assisted GPS system which triangulates your location based on the cell towers you are near. Some have reported success with this, while others have not.
I am on T-Mobile, and it is giving me an error: "Unable to locate any known cell towers". Could it only work with AT&T? Or am I just in a lame place? Your thoughts... Please post your area along with your results.
UPDATE: Works fine on T-Mobile, assuming you're in an area it knows. Not sure yet where it gets it data, as far as where it will know and where it won't. But I went down near the Tampa International Airport, and it definitely knew that area. So it works on T-Mobile!