What now!?
Well first... here's a video....
It shows all 4 traps in action, using Visual Debug Mode.
So you can see all the hidden stuff, and all the important geometry is nicely highlighted.
My aim in designing Gotcha! was not to trick you, trap you and kill a lot of unsuspecting Goos....
although I'll admit it was fun... 
I know some of you are already thinking about designing similar levels.. or levels that do similar things...and I look forward to playing them... but consider this....
My aim was to show that you can use the physics stuff in World of Goo to create some quite complex "mechanisms".
OK I used them for traps, but that's not the only thing they could be used for.
I can think of plenty of situations where very similar setups could be used to HELP the Goos not just to HURT them.
(See the "Do Not Pull" lever in Trap #3)
They can now open doors, without needing a Bomb to blow them up. They can pull levels and push buttons that actually DO something. A group of goos in one area could complete a small task and open a trap door for other goos in another area.
In short, I believe this is the start of something wonderful... we can now set proper "problems" for the Goos solve...
the possiblities ARE endless.
Have fun! 
DaB