This article is too short to display the intricacies of what happened. For people more interested in the exact reason why he didn't accept the millennium prize from the Clay Institute and the nature of his proof to some slightly more rigorous mention (although the full proof is readily available on arXiv), please read this phenomenal piece written by The New Yorker in 2006, found here: http://www.newyorker.com/archive/2006/08/28/060828fa_fact2
This happened about a year ago... A big part of rejecting the prize came from his desire to have nothing to do with the math community as a whole. Accepting the prize would be acknowledging it's place in the world.
"To put it short, the main reason is my disagreement with the organized mathematical community," Perelman, 43, told Interfax. "I don't like their decisions, I consider them unjust."
While I can applaud the purity of his dedication to mathematical research, if I were him, I'd take the money. How often will math make you a million dollars?
