Reverse Geocoding Without Web Access

Question

I am working on an application where one of the requirements is that I be able to perform realtime reverse geocoding operations based on GPS data. In particular, I must be

Answer 1

If you can get hold of state boundaries as polygons (for example, via OpenStreetMap), determining the current state is just a point-in-polygon test.

If you need address data, an offline solution would be to use Microsoft Mappoint.