A new version of the Virtual Earth SDK is out, that's the very nicely done interactive SDK at dev.live.com. New features include:
Add Custom Tiles:
Generate map tiles using the MapCruncher from Microsoft Research to add custom overlays, in varying transparencies, to your maps:
"The Virtual Earth API allows web developers to supplement Virtual Earth's maps with pushpins and lines. MapCruncher brings mashups to a whole new level by allowing developers to import entire maps to supplement the existing road and aerial imagery with detailed, application-specific information. The possibilities are endless: bicycle maps, transit maps, national park maps, university maps, antique city maps, or whatever drawn-to-scale maps you personally find interesting. You can even augment Virtual Earth with Do-It-Yourself Aerial Photography. See our Gallery for more examples"
Draw Polygons:
The VE Polyline feature has been expanded to support filled polygons, again with varying transparency
Disambiguate Address:
A new VESearchResult object lets you work with returned addresses from a VEMap.Find method call.
Change the Map Scale Bar:
Change the map scale bar to miles or kilometers.
For more on some interesting uses of the new controls, check out these two entries in the Windows Live Local/Virtual Earth blog:
Map Controls to the Extreme!
Thematic Mapping and Shaded Area Maps with Virtual Earth