Browsing through AppleInsider’s image gallery of Google Earth for OSX screenshots, I came across the About box. Note the line “Operating System: Mac OS X”, which to me suggests that the application is the product of a multi-platform development effort. This would gel with the look and feel of the buttons in the other screenshots, which some commenters on the AppleInsider article have said looks like earlier versions of the OS, circa 10.1 and 10.2. To me, however, it looks more like an X11- or Java-based application (just like WW2D, in fact). I could be wrong, though:-)