I just noticed some interesting features using a track pad with my 2012 imac running 10.8.5.

I click and drag a file from one window to another. I click and hold with my thumb and use my index finger to move the cursor with the file to another window....

NOW... I can use a third finger to tap (I have tap enabled in the sys prefs) on a different window (or a different application) to bring it to the front.

I can also use two fingers to scroll in the other window while still holding the dragged file with my index finger.

I can also use the rest of my fingers to do a three finger swipe to invoke Mission Control. And since I have Totalspaces installed, I can also use a horizontal three fingered swipe to move to different spaces.

How long has this behavior been in the OS? What other similar multifunction maneuvers are available?

The 'let me do all sorts of crazy crap while holding a file' has been around since at least the glass trackpads, if not earlier (have to double-check on my wife's early 2009 MacBook).

Groovy, eh?

very groovy... I especially like that I can scroll while holding a file...

not like me to take so long to find these things... I'm always experimenting... I just assumed that it was new to 10.8 - glad I asked...