Why?
TerraGo Technologies?
in-q-tel.com/news/releases/10_ ...
and
www10.giscafe.com/nbc/articles ...

1) Adds more usability Google maps, Google Earth and other GIS based maps.

2) Revenue stream, especially for their fee-based version of Google Maps?

3) Why this company?
It just received venture cap funding from the venture cap arm of the CIA, In-Q-Tel.
in-q-tel.com/index.htm

2 other services that received funding from In-Q-Tel have been acquired by Google.

A) Keyhole (aka Google Earth)
See:
in-q-tel.com/news/releases/06_ ...
google.com/press/pressrel/keyh ...

B) Google Acquires @Last Software (Sketch-Up)
in-q-tel.com/news/releases/03_ ...