Some members of the VSSDK team (namely Patrice Pelland and Anthony Cangialosi) have been working on getting some screencasts up onto Channel 9. These are excellent if you're just getting started with using the VSSDK and need some advice on next steps to get going:

Also, the VSSDK now has a shorter URL (and direct from microsoft.com) to get to the VS Extensibility Center where you can download all the latest bits on VS extensibility:

http://www.microsoft.com/extendvs