Google Mars is a new web site launched by Google, with the same philosophy of Google Earth: you can see each part of Mars, as observed by telescopes.
Now you can see the red planet in the same way you can see the earth. In a sense, Mars is now much closer than it ever was, thanks to Google technology.
From the Google blog:
In commemoration of Lowell's birthday, we're pleased to bring you Google Mars. Explore the red planet in three different ways: an elevation map shows color-coded peaks and valleys, a visible-imagery map shows what your eyes would actually see, and an infrared-imagery map shows the detail your eyes would miss.
There is no doubt this is one of the coolest projects projects released by Google!
Link via Google blog