With the classic example from the of drag and drop there are at least 96 interesting moments (6 actors X 16 events = 96 interesting moments).
About a month back I gave a talk at Zurb, a northern California design firm, in which I discussed this technique. On Friday I was pleasantly surprised to see they had already taken the idea and used it in a new product they announced last week -- BounceApp -- which was featured on TechCrunch.
Check out their article on 110 Interactions for Editing Annotations on Bounceapp.com.
Nice application of the grid.