flash actionscript: Is it possible to stagger transitions (zoom, wipe, fly, iris, etc.); for
example, attach a movie that appears on stage with a wipe effect, and when
transition is complete, attach a second movie that appears on stage with a
transition, and so forth. The tween class has onMotionFinished. Is there a
similar approach?

That's probably the number one reason I don't use the TransitionManager Class.
It's great for quick effects but I can't find a successful way to chain
together things into a more complex animation. Might involve writing a custom
Class or something. If nobody has an answer for your problem that's the only
solution I can think of short of just using the Tween Class.

--Mike

TransitionManager uses EventDispatcher:
this.dispatchEvent ({type:"allTransitionsOutDone", target:this});
That should create possibiities to capture that event in your 'next' object.
Examine the TransitionManager class.