The 2011 physics Nobel prize goes to Saul Perlmutter (50%), Brian Schmidt (25%), and Adam Riess (25%) for their observations of distant supernovae.
These 1998 (Perlmutter) and 1998 (Schmidt+Riess) observations were important because they revealed that the cosmological constant is positive.
This insight helped to throw fundamental physics to an amazing mess – which it hasn't really left so far – and energized various somewhat pseudoscientific approaches within theoretical physics such as the anthropic principle, something that hundreds of TRF blog entries have been dedicated to. This mess is not necessarily the astronomers' fault; it may still be due to the theorists' inherent stupidity.
Aside from the crisis that the observation helped to bring (by something we have often called the most stunning experimental discovery of the last 15 years), the prize is also a reminder for experimental physicists who are dreaming about a Nobel prize that routine work combined with some lucky hunch and one package of good luck is enough to win the award. ;-)
Of course, I do believe that Perlmutter in particular is an extremely good astronomer. However, I don't understand how the sociology of the large experimental teams works but I feel that there's a significant amount of politics in the question which individuals get such awards.
Congratulations to the winners anyway but yes, I agree with Graham Farmelo and others that top theorists are being screwed relatively to experimenters without adjectives. The folks are still famous: you find Perlmutter's name in five TRF postings so he satisfies this condition for fame. You may also find a Brian Schmidt on TRF but he claimed to be a layman. ;-)
Yesterday, the 2011 medicine Nobel prize was given to three immunologists, by the same 50-25-25 template. Unfortunately, they didn't notice that the winner of those 50% had been dead since last Friday: this suggests that the relations among the physiologists are not exactly cordial. The Nobel committee kept him as a winner and therefore violated one of the rules for the Nobel prizes.