Check this out: I just played a game where the right strategy on the final turn was to pass a colony to my opponent using my masquerade!
The game itself is pretty boring, I just go BM-masq because I don't see good enough engines on the board. My opponent actually builds a successful engine, and because of it, he probably would have won if he went for the possession sooner. Since I had a masq and colonies, I had to prevent him from playing it at all costs.
On my final turn, after I play the masq and draw the 2 cards, I'm looking at exactly $11 and two colonies. So I pass him one of the colonies so I can keep my money and buy out the last colony to end the game!
Unfortunately, since the game log doesn't show the passed cards using masq, I don't have proof. But here's the log anyway:
http://dominion.isotropic.org/gamelog/201208/17/game-20120817-234123-e9eec4de.html
