I don't know how long this has been part of the game, probably since 1.7, but I just discovered I can now use "Desktop Fullscreen" mode in OS X by way of the specific Fullscreen button on the window titlebar and it will go into "Lion Fullscreen" mode instead of using F11 and setting it to normal fullscreen mode which takes over the entire system's graphical interface and disallows tabbing out.
Basically, in the regular fullscreen mode, which you press F11 to activate, Java will take over your display, set your resolution to something else, and disallow you from switching apps until you exit out of fullscreen. As much as I liked this mode, it had the tendency to occasionally freeze up. And when a fullscreen app freezes, you can't kill it. So I would have to force shut down. So I found myself just running windowed more often.
But now I know I have a proper fullscreen desktop mode which adheres to OS X's rules of making the window into a fullscreen "space" that I can switch between with trackpad gestures like a normal OS X user can.
I know it sounds silly to outsiders, but as a Mac user I am very happy. I don't even know how long this feature has been here. I'd been using F11 like a sucker. Which on my Retina Pro would set the display resolution to 1280x800 and looked like shit compared to windowed mode. Now I can run it in the 1920x1200 resolution I'm currently using and not lose any visual quality. Plus I can swipe between apps and have MineCraft on its own space instead of covering my desktop.
I'm so happy now.
For the layman, some visuals...
Basically you click this button:
And it makes any supported window or app fullscreen, but lets you switch between them with a gesture like iOS on the iPad:
With a swipe to the left or right with four fingers, I can switch between my apps super quick without my hand leaving my trackpad.
Thank you based Jeb.
Now if only I could somehow remap F3. You can remap most other F-commands, but not the others. My F-keys are already taken up by other things, Mojang. Let me change my debug key! If I go into "normal" fullscreen I can hit the F-keys with no trouble because Java is currently taken over the entire system, but in windowed or fullscreen desktop Minecraft is assuming you're not using your F-keys for anything. But I use Better Touch Tool to as assign these keys to open apps and stuff. F3 for me is Sublime Text. So I can't show my debug information unless I hit my normal fullscreen button first then F3 then exit out, or quit BTT. Just let me change that key!