David,

I think this one sums up Hayek's main contribution best

 > It is no exaggeration to say that if we had had to rely on
 > conscious central planning for the growth of our industrial
 > system, it would never have reached the degree of
 > differentiation, complexity, and flexibility it has
 > attained. Compared with this method of solving the economic
 > problem by means of decentralization plus automatic
 > coordination, the more obvious method of central direction
 > is incredibly clumsy, primitive, and limited in scope.  (96,
 > The Road to Serfdom).

On the other hand I think this one sums up why the profession has not 
understand Hayek's main contribution all that well.

 > I am far from denying that in our system equilibrium
 > analysis has a useful function to perform. But when it comes
 > to the point where it misleads some of our leading thinkers
 > into believing that the situation which it describes has
 > direct relevance to the solution of practical problems, it
 > is high time that we remember that it does not deal with the
 > social process at all and that it is no more than a useful
 > preliminary to the study of the main problem." (530,
 > The Uses of Knowledge in Society, AER, 1945).

Doug Mackenzie