I was just saying this to myself when this article popped up. Developing iApps with XCode, I set it to full screen, but when it comes time to run the app in the iPad simulator, that is a separate app. I want that to be on the second screen, but in full screen you can't do it. In full screen, you do get some more real estate in the window, but I can't use it because of the simulator problem.
Full screen should go full screen, but not all-screen. Let the second monitor be another desktop so you can have a second app, perhaps also full screen, on it.
I'm learning python, and since I can't get GASP support to work in OSX, I'm coding in Ubuntu, running in VirtualBox. I cannot tell you the number of times I've hooked my MBP up to my 20" monitor, and needed to run VirtualBox in full screen on the 20", while having the tutorial I'm using on the screen of my MBP. It's just far too useful.