You can get surprisingly good location data without GPS, if you have network access and at least one common radio: there are a number of outfits who build databases of wifi APs, cell towers, and similar(Skyhook is one; Google’s ‘street view’ cars also do RF sniffing, not sure if Apple farms it out or does it in house).
The databases are fairly large; and need to be current to be useful, so offline use compares poorly to GPS(if the vendor even gives you the ability to see the database itself, not just submit location queries); but it works pretty well in reasonably thickly settled areas with lots of RF sources.
