So, what was he showing to Steve? Why his application which is called EZiD. It creates 'decks' of like windows to clear up cluttered screens. Sounds a lot like the rumored 'Piles' feature that Apple was playing around with for awhile, though for windows (as was pointed out in the comments).
The app is clearly not ready for prime time (it didn't work on my MacBook Pro), but I am sure Martin got lots of great pointers at WWDC.
Now if you'll excuse me I am going to ponder exactly how Steve can fire someone who doesn't work for him. The man is powerful.