Streetmap.co.uk do actually provide a mapping *application* for the SPV
called Pocket Streetmap. This program will download maps from the internet, using GPRS, and will store these locally on the device so that repeated visits and web connections are not necessary, eg try looking at a map when traveliing underground by tube :-)
The program can happily use any type of net connection, eg cradle to PC etc, so that larger areas of map data, eg city, can be downloaded where the cost of connection is not an issue. Maps can be stored both on the device memory and the data card.
Optionally, the program can use GPS receivers to track current position and provide other facilities related to position.
The program is currently is restricted beta (preparing for certification). Samples of the European map data ( London Soho ) can be seen by pointing the SPV internet web browser athttp://www.streetmap.co.uk/smarthpone/sample.gif