Unfortunately, it's Windows only for now, but the program is pretty awesome. I set all kinds of bookmarks for all of the big landmarks around the world. It's cool that they were able to get the data for the rest of the world... I don't remember maps.google.com having that.
http://earth.google.com/
If anyone finds cool landmarks, post the Lat/Lon so we can all bookmark them. When I dig out the windows computer, I'll post mine for the Pyramids in Egypt and some other cool ones I stumbled across.