Like many people I am fascinated by maps from Google and now from Microsoft. I still find Yahoo maps more useful because they are plain representation of local information and somehow I find them richer in information. This may be my familiarity with them — I did not try any objective experiment.
These realistic maps from Google and MSN are the result od availability of the satellite and aerial images. This in turn is the result of the efforts of space agencies, possibly most notably NASA, over last several decades. NASA has been collecting all kind of data, overlayed on images, for very long time. It is just that finally technology advanced to the stage where the benefits of the NASA research can be shared directly with consumers. Good thing is that what we have seen is just the beginning of an interesting direction.
Today when I see images or maps from Google, I usually see old images. Satellites are regularly sending images for weather analysis and other observation purposes — see Earth Observing Systems Project page — and these images give current status of the earth. Now imagine that in a few years these images could be available to use in our planning or for whatever purpose. That means that you could observe what is the current status of a particular location. You can than mashup these images with some other realtime data and that starts the beginning of a (near) real time observation system for any place on the earth. ANd you could also analyze the changes taking place at these locations.
Effectively, this will being the technology that is currently used for weather prediction to your desptop — sorry to your phone. This is not scienc fiction — this is likely scenarion in just a few years from now.
This could be an interesting direction for some innovators. The major revolution in maps started — among other things — when Keyhole technology was acquired by Google. People like to talk about the Next Google, it may also be interesting to think about the NEXT Keyhole.