Finally, some hints that it's actually under development (remember that most of it is inherently portable):
Via Alexandre, here's the AppleInsider piece where I got the screenshot . They confuse Earth with Maps (they are actually two slightly different databases) and say that the file has been making the rounds "overseas", but nobody I know got any hints of that...
Since I use it on a daily basis on Windows, I hope it's released soon (and who knows, given the components it's based on, Linux folk might also get lucky).
But I also hope and that it works on real high-resolution displays - it should work fine on my iMac G5, but in case you don't know, the last Windows version I have crashes when I crank the resolution beyond 1600x1200.
And yes, I need that sort of resolution for the data I'm layering atop it...