The Academy has spoken, as expected the NASA COBE mission measurement of the cosmic microwave background won the Physics Nobel prize, with the award shared equally by John Mather at NASA Goddard and George Smoot at Berkeley
This is a well deserved award, although I expect several people will be wondering why they weren't recognised for their contribution to the mission's success with a share of the prize (and that of course is the problem, arguably several people were comparably worthy in being the third recipient, and there are never more than three people named).
COBE was an amazing medium class mission which generated an all sky infrared and microwave map of the sky.
After subtracting the foreground emission from the solar system dust and the Milky Way galaxy, this produced a moderately high resolution map of the microwave sky, yielding a very accurate measurement of the mean radiation temperature of the sky (2.73 Kelvin for Astro 001 students), which is the diffuse radiative glow left over from the Big Bang, after cooling for 13 billion years or so as the universe expanded.
COBE also got good measurements of the long predicted fluctuations of the microwave background due to the tiny ripples and inhomogeneities which eventually grew into all the strucute we see in the local universe. This was an astonishingly precise measurement, later confirmed by a succession ground based measurements and the WMAP successor mission.
Combined with other cosmological measurments, this has very solidly verified the predictions of the Big Bang model, and, successively the additional predictions of a Cold Dark Matter dominated universe which underwent an inflationary phase, and, most recently, the realization that Dark Energy is still contributing to the energy density of the universe.
PS: interesting side effect - if there was any doubt, this will definitely lock JWST into place as a Mission That Must Be Done
Congratulations to John M. whom I met at AAS, and George S. who is frequently seen in Berkeley. We should look forward to Planck results around 2010. Has anyone noticed that the writings have backed away from the "lambda-CDM" cosmology touted by the later WMAP team?