Google Maps + Flash + MSN Virtual Earth = FlashEarth

Here is an alternate, if somewhat limited, Google Maps viewer which also aggregates MSN Virtual Earth - using Flash. The creator of the mashup states that "unfortunately Flash can't read Google's roadmap images because they're the wrong file type (Flash can currently only read JPEGs)" but mentions "it's something I'm hoping to add when the next version of the Flash Player is out in a month or two's time."

The mashup/alternate viewer is called FlashEarth and can be found here. There is more information on a blog entry here.