Nice Review of the Extension Manager
Chris wrote a nice review of the VS2010 Extension Manager feature at TechRepublic. Having worked on the team that wrote that feature, it's always nice to see a positive review of what you've spent your effort working on. As Chris also noted, there is still more work that needs to be done to round out the Extension Manager experience. But, we hope that its first incarnation will fuel the use and development of new extensions for Visual Studio. We've already seen a lot of new extensions go live right around launch of VS2010.
One thing I'd like to make clear from his article, Chris talks a lot about MEF extensions and the Extension Manager... and there are definitely some interesting, new MEF extensions that have already been build for VS2010. But, the bulk of the extensions on the Online Gallery are packages (for designers, tool windows, menu commands, etc), toolbox controls, and templates, which are not MEF based at all. The new deployment model we implemented for this version (the VSIX file), supports all of those methods of extending Visual Studio... not only for MEF extensions.
As a matter of fact, your extension doesn't even need to be deployed in a VSIX file to show up in the Online Gallery. The Extension Manager will also show MSI-based extensions that can be installed from the VS Gallery. However, those types of extensions cannot be managed (enabled/disabled/uninstalled) through the Extension Manager... that must be done with the Windows Add/Remove Programs.