I have been working with Marc Postman and (initially) Josh Perlow on the possible use of the GoogleSky plugin to produce a mashup that could test the capabilities of new tools to do or enable science.
Above is the initial result of the integration of a study of Brightest Cluster Galaxies (BCG) and a database interface to compute simple (for now) quantities and visualize them.
This project is in its infancy, but the potential of the API from GoogleEarth/Sky is in my opinion obvious. Once can take a look at what's possible, by clicking on the SIMBAD objects at the bottom of the plugin and seeing how a regionated KML can be easily loaded. This KML in question was demoed at ADASS by Sebastien Derriere and it's also a demonstration of what kind of applications one can think of when using a well defined standard like KML.
Massive, and I believe revolutionary (for astronomy), mashups are on the way!