Grigory Perelman, a Russian mathematician who may have solved Poincare Conjecture, has won the Fields Medal for his work on the Ricci Flow. The Fields Medal is one of the most prestigious prizes in mathematics and is awarded every four years by the International Congress of Mathematicians. This year, the awards were presented by King Juan Carlos of Spain. Interestingly, Perelman has made news by not showing up to the ceremony to receive the Fields Medal. The New Yorker has recently done a story on him.
Perelman has also gained international notoriety for posting a generalized solution to the Poincare Conjecture on a web site in November, 2002. Many mathematicians believe that he may have successfully solved it. It is a statement to Perelman's reputation that mathematicians have been willing to come to his web site as opposed to the standard process where Perelman would submit his papers to a peer-reviewed math journal.
The Poincare Conjecture is a theorem about the nature of multidimensional space. It is the most famous open problem in topology. The Poincare Conject concerns the problem of transforming a torus into sphere.
If Perelman has indeed proven the Poincare Conjecture, then he will be eligible for the $1 million from the Clay Mathematics Institute. The Institute has identified seven open math problems which it has called the Millenium Problems and offers a $1 million prize for the solution of any of them. Perelman has said that if he wins the $1 million dollars, he plans to talk to the Institute.