As you’re aware, Apple just released iTunes 10. With that release has come some changes—both expected and not so.
An unexpected change is that iTunes Automator actions no longer load. This affects both existing workflows created for an earlier version of iTunes as well as any workflows you create with iTunes 10 installed. Those existing workflows simply won't execute. And if you attempt to create new workflows that include iTunes actions, you'll discover that the iTunes actions don't appear in the actions library if you've installed iTunes 10.
This bug should not affect AppleScript support in iTunes.