He forgot one: make multiple monitors finally useful on OSX, especially with the advent of full screen apps (current behavior is just display a gray texture on other monitors instead).

Seriously, if 10.9 is announced with that feature alone and nothing else, I will buy 10.9 if it fixes this.

The behavior actually depends on the app. If the application can't figure out a good way to use both screens, then you get the gray texture on one screen.

Yes, but I want to display a full screen app on each monitor, which is the only sane way to use that behavior.

Discussed here: https://news.ycombinator.com/item?id=5722532