As I mentioned before, WSS 3.0 support is something we're hoping to include in our next version, so I'm glad to see these extensions that help make it an even better platform for development! Woo hoo!
The extensions (as they're known to their friends) were designed specifically to jumpstart developers creating SharePoint solutions in Visual Studio. They include project and item templates for essential SharePoint building blocks like Web parts; team sites, blank sites, and list definitions; custom fields, content types, and modules. Each template includes functionality that makes coding, testing, and deploying these items easier than ever before. If you intent to develop in the SharePoint environment using Visual Studio, this download is for you.