I have created an extension for VS 2010 that deploys a project template. The project template uses a custom wizard (in a specific assembly) that is called when I create a new pr
You don't need to get your assembly containing the IWizard implementation in the GAC. You can simply declare it in your extension.vsixmanifest file as an Assembly element in the Content section.
Unfortunately, this doesn't appear to be documented well anywhere.
The only tricky part is making sure that the AssemblyName attribute has the correct value.