Poincaré's Conjecture

There was a really nifty story on NPR this morning about a reclusive Russian mathematician, Grigori Perelman, who appears to have solved a famous mathematical problem called Poincaré's Conjecture. There's plenty of material about it on the web, e.g., (1)(2)(3). A million dollar prize is on offer for the solution of this problem (and another $1,000,000 each for six other problems) from the Clay Mathematics Institute.

There's a chapter about the problem (not the new solution!) in Keith Devlin's 2002 title, The millennium problems : the seven greatest unsolved mathematical puzzles of our time; and a lot about Poincaré (but not the Conjecture) in Einstein's clocks, Poincaré's maps : empires of time by Peter Galison.