It's a canvas element that they render to now. It's very similar to the previous Flash implementation, in that it's an area of the screen they can draw on. It just happens to be in Javascript instead of Actionscript now.
But if i go to maps.google.com and zoom in, it apparently is using flash and doesn't work. The linked site does work. I'm guessing there's some API you can use for google maps, and it uses the non-flash version. But is there a way to use the non flash version on maps.google.com?