[net.puzzle] another hat puzzle

gwyn@brl-smoke.ARPA (Doug Gwyn ) (02/11/86)

Three men (could be women, but these are men's hats) are in a room.
They are blindfolded and one black hat apiece is placed on each
of their their heads.  The blindfolds are removed and they are
told:  "Your hat is either red or black.  Not all three are red.
The first one to tell his own hat's color without looking at his
own hat wins a prize; if you guess wrongly you pay a fine."
Some time passes; finally, one of the men speaks up and wins the
prize.  Explain his reasoning.

(Please don't post your answer; you'll know if you have it right.)