I think it's a research tool. To participate, one just need a Google Account.
Pretty interesting... and definitely exciting for the user because we know that we are contributing to the construction of the 3-dimensional look of the map!
To do this, one needs a photo of a building/ structure. Then identify area to be 'mapped' onto the googlemap. Pretty easy to do.
As for teaching and learning, it's still quite obvious for meaningful integration, although we would usually thought of Geogaphy (because of GoogeMap/Earth) and Mathematisc (because it deals with shapes).
The next step is... to find a natural fit into the subject topic...