I'm glad you posted that, Doug, because I was racking my brain, trying to think of when I'd heard about this before!
It's pretty neat. I can think of several things I'd like to see added to it that would make it more useful to me but probably needlessly (and confusingly) complex for the people they're aiming this tool for. As it is, it's pretty cool to watch it in action. What I've had the most fun with so far is spinning around in the Mission Overview window, seeing how the shape of Cassini's orbit passes through the other moons' orbits, and specifically noting where it crosses Titan's; then you can see how every time Cassini and Titan are in the same place at the same time, the orbit bends.
Neato.
--Emily