vagabundo
Adventurer
This is where page 42 of the DMG comes into play. As the example of the Acrobatics check and the chandelier shows, the GM is meant to set DCs for non-power-based stunts that reflect not just the difficulty of the action in the gameworld, but the suitability of the action to the narrative (ie do we as a gaming table want to see more or less of this sort of stuff going on?).
I think this part of GMing 4e is actually quite challenging, because it can affect the mechanical balance of the game if the GM is not careful to keep stunting at a lower level of effectiveness than powers, but it can affect the narrative satisfactoriness of the game if the GM is not highly permissive in allowing all sorts of stunting.
Pukuni, I hope I'm right in remembering that you've followed a lot of LostSoul's threads on how to use page 42 to handle this sort of thing. I'm going to start GMing 4e fairly soon, and will certainly be relying on a lot of LostSoul's ideas for guidance and inspiration.
One thing I'd like to add here, and it is something I initially missed, is that the tumble utility is an exception, a freebie. This ability was moved to the acrobatics skill - stunt - and the ability was opened up a little in scope for juicy swashbuckling action.
There are a lot of subtle changes that I missed on my first read through and knowing the ins-and-outs of 3e hindered me.