Cellular mobile devices and Google Maps can be used to provide fast and accurate localization without GPS. Using a database of cell coordinates, the location of an object can be precisely determined.
The cell names, coordinates, and the maximum distance allowed between the cell and the phone before it switches towers must be known first in order to find the position. That information can be compared to cell databases provided by Google, cell phone companies, or even open source projects. Because the circular coverage of a cell is already known, the location of the cell phone can be determined.
Open Electronics has a full series on localization techniques with GSM cellular devices.