How to include the Title field of a content type inside of a Group?
There is only one way I'm aware of to do this. But since this solution is structural, it may not make sense to use it since the goal here is more for admin-usability.

You could use the Automatic Nodetitles module ("ANT") create a new CCK field for the title, put it in the fieldgroup that you like, and configure ANT to populate the true title field from that new custom CCK field.