Toyota’s Customized Map Updates

Just how hard is it to update the maps on in-dash GPS navigation systems? The fact that Toyota’s announcement — that it has developed a way to simplify and speed up the process by only updating the maps relevant to the driver — is getting the attention it has (Far East Gizmos, Engadget) suggests that it is pretty involved; the news release says it’s normally done twice a year, with the resulting delay in getting new map data to drivers. I suppose there’s a problem along these lines whenever map updates are done physically — for example, CD-ROM maps for GPS devices — rather than over a network.