At Macworld we rarely look at beta software, but this is something special. Google Earth is an application that uses satellite images of the world to make a fully zoomable globe. It's been available for Windows in beta form for a while, and while Google has said it's working on a Mac version, it hasn't been officially released yet. We have, however, been able to look at a pre-release version.
First off, the system requirements mean that some older Macs won't run Google Earth. Again, the official requirements haven't been released yet, but as long as you have a pretty decent video card, or a Mac that's less than three years old, you should be fine. The other thing that is needed is a broadband connection. Because the maps are streamed as you zoom in closer, the application needs a speedy network to deliver them smoothly.
To get you started, and to explain how Google Earth works, there is a preloaded tour. Various highlights are marked around the world, such as Nelson's Column, the Grand Canyon and the Taj Mahal. By clicking on the play button you are flown from place to place, zooming in and pausing at each amazing view. There are various layers that can be turned on, such as roads, borders and even dining (though most work only in the US). In some US cities there is even 3D data available and Google integrates those 3D images into the maps. So when you swoop down on New York or Chicago you get buildings standing out of the map. Terrain is also available in some areas, so Mount St Helens and the Grand Canyon are shown in glorious full relief.
There is a pretty big list of layers that can be added. As mentioned most are US only, but it does seem that coverage is growing quickly around the world. These layers include such things as coffee bars, banks and restaurants.
Actually, using Google Earth can be a little disappointing if you don't happen to live in a big city. The images are all seamlessly stitched together from satellite pictures, but the highest-resolution images tend to cover only very populated areas like cities. While I found my house quite easily, looking for my brother's house in Usk, a small town in Wales, was less successful. Not only could I not see his house, I barely even found the town.
Likewise, I was able to find my old apartment in Chicago with relative ease, but when tracking my movements when I moved north to Wisconsin the resolution quickly dropped. The good news is that the maps are constantly updated. Google claims that the images are no more than two or three years old, although I'm sure some of the views I looked at seemed older.
Another useful feature is the Google Earth Community layer. This is a layer of interesting features marked out by members of the public. So if you know of a nice spot or handy point of reference, such as a local castle or a nuclear reactor, you can mark it out for others to find.
The good news is that Google Earth is as addictive as the Web was when it first came out, and it seems as if it is only going to get better. The bad news is that the Mac version isn't quite ready yet, though this pre-beta indicates it must be nearly finished. When it does come out it should be free, like the currently available PC version. There are more advanced versions available for Windows, but it's not clear if these will be available for OS X. Google Earth Plus offers GPS integration, but considering that few if any GPS units are Mac compatible it seems unlikely there will be a Mac equivalent.