has gone to, among others, my former professor, Eric Maskin. Rather than try to summarize his accomplishments myself, I'll just refer you for now to Marginal Revolution (actually, just go to the main page, as there are a bunch of posts, and there may be more later) and the sources linked there.
The Austrian Economists blog has several informative posts discussing the winners of the Nobel Prize in Economics. According to Peter Boettke, writing in today's Wall Street Journal, much of the early work on mechanism design was spurred by Mises and Hayek's challenge to socialist economic planning. (Boettke's column presumably is subscriber only as it is not on Opinion Journal).