Fascinating to see something like HistoryPin emerge, especially with a Google partnership, and the engine that comes behind that:
Very promising idea. Geolocated augmented reality data with mobile devices has been difficult to get to work properly on a large scale in the past, such as with Wikitude and Layar. I assume the AR overlays are the logical progression of where this service is going long term, although it appears also to be a desktop system as is. But if you test this out, let me know how it works for you and what you think.