All Points Blog points to a forthcoming iPhone/iPod touch application called Old Map App, which, the developers say, “displays layers of geo-referenced historical maps projected onto a modern coordinate system, so that the same location can be compared over time. Layers can be faded, adjusted, and explored freely. If the user is located within the region of the historical map, the user’s position will be mapped on the old maps to the position of the compass indicator.” The site has a short video demo.