Use Google Earth from your browser, by installing the Plug-in which works in Firefox and Internet Explorer. The plugin makes it easy to use Google Earth without installing the application.
“The Google Earth Plug-in and its APIs lets you embed the full power of Google Earth and its 3D rendering capabilities into your web pages.”
The Google Earth API will allow web developers to quickly and easily turn their web pages into 3D map applications with only a few lines of code.
It also allows a user to build 3D Google Sky i.e. to overlay content over different planets, stars, and galaxies by toggling Sky mode.
All these changes were done with an intention of creating great geo-based 3D application, and change how we view the world.
Download plugin at http://code.google.com/apis/earth/