One can only assume that over time, Google Earth, will be able to "playback" the evolution of a community as it grows. As more of a physical space is mapped into the database they should be able to let you pick a point in time and see how the community looked at date x. We've kicked this around and it seems like it would be fun to see but I can't see why anyone would pay to experience it. Waiting 25 years for something significant to happen will also be a bit of a drag. On the other hand, it does get the mind wondering on how you might populate the database without waiting.
I assume that tax records exist going back some significant number of years. The valuation associated with each parcel would provide a clue as to the use of the land. Zoning records would provide some reference as to the intended use of the land. Working from one or more of these records it would, theoretically, be possible to replay the evolution of a community over time. With clever modeling, a system such as this would be very helpful in understanding the environmental impact of development, patterns in land use, etc. I would guess that correlating watershed environmental health to the patterns of urban development would be useful to someone.