Signed audio units

Looks like audio units and other plugins will be subject to Mountain Lion’s Gatekeeper.

If you are distributing Mac software or audio plug-ins outside of the Mac App Store, Gatekeeper will affect your users who adopt Mountain Lion and download your software to install. In order to make your software Gatekeeper-compatible, you will need to join the Mac Developer Program and get your Developer ID.

…you can’t sell plugins on the Mac App Store.