In addition to Google Earth and Bing Maps now comes Marble

In addition to Google Earth and Bing Maps now comes Marble, a virtual globe application for free as an alternative for users of Linux, Windows and Mac OS. For users of Linux, open source applications are coming along with the KDE desktop, though it can also be run in GNOME.

Marble like Google Earth and Maps Bing, also can display satellite imagery, satellite imagery is available as well as night visual, map of ancient globe in 1689, temperature and precipitation information. Even the available display the Moon, Venus and Mars.

Marble is able to display data from OpenStreetMap and Google Earth KML file open maps and GPS data GPX data file. Marble can also view an image similar to the Panoramio layer in Google Earth, find the coordinates with the different projection systems and available Map Creation Wizard and Folder Sharing and measure the distance between one location to another.
Here's a video that presented the ability of Marble

You can download Marble which supports various operating systems from the developer website via the link below:
Download Virtual Globe Marble