From the video page:
"Project Astoria" lets you build great Windows apps, while reusing your Android app code and tools.
Apps built with this technology leverage key Windows interactions, and deliver the kind of experience Windows users expect.
To make changes or debug your app, you can use your current IDE. We support IntelliJ, Android Studio, and Eclipse, and in addition to Windows development machines, you can use your Mac.
And here's the very nicely done video:
There's more on Project Astoria here.
And see also an expert's view - Rudy Huyn, possibly the rock star Windows Phone developer in the ecosystem, has weighed in on Project Astoria. As we discussed in the AAWP podcast last night, only very simple Android applicatons will be instantly usable, and he fears that anything 'meaty' will either take a lot of work or end up having to compromise on functionality or experience.