It's that time of year again - time to speculate about the Nobel Prizes. Physics gets announced Tuesday, followed by Chemistry the next day. While I feel almost obligated to mention my standard speculation (Aharonov and Berry for geometrical phases), it seems likely that this year's physics prize will be astro-themed, since there hasn't been one of those in a while. Something related to dark matter perhaps (Vera Rubin for galaxy rotation curves?), though direct detection of dark matter may be a necessary precursor for that. Inflationary cosmology gets mentioned (Guth and Linde?) by some. Extrasolar planets? Fine scale structure in the cosmic microwave background as a constraint on what the universe is made of? There certainly has been a lot of astro excitement in the last few years.... Feel free to speculate in the comments.
Update: The 2011 Nobel in Physics has been awarded to Saul Perlmutter, Brian Schmidt, and Adam Riess, for their discovery (via observations of type IA supernova) that not only is the universe expanding, but that expansion is (apparently) accelerating. Makes sense, in that this work certainly altered our whole view of the universe's fate. Combined with other observations (e.g., detailed measurements of the cosmic microwave background), it would now seem that the universe's total energy density is 4% ordinary matter, 23% dark matter (gravitates but otherwise interacts very weakly with the ordinary matter), and 73% "dark energy" (energy density associated with space itself). For a nice summary of the science, see here (pdf). Congratulations to all!