I can get around Tokyo for the most part at a gross level--as in I can find parks, railroad stations, and the like. But I think I spent an hour the last time I was there searching for my company's office. Guidebook authors should start thinking about including GPS coordinates although increasingly, given a network connection, it's a moot point given Google Maps.

Does anyone know what the market leader for GPS (for native and non-native users) in Japan is?