Summary

CMB is the most ancient light we will ever be able to observe
Before that Universe was opaque
Maps of the CMB show structure of the Universe 300,000 years after the big bang
pattern matches detailed theoretical predictions
is used to measure cosmological parameters
one of the cornerstones of the standard cos. model
but this model is absurd!
CMB polarization is an important test of the paradigm
may also allow us to see gravity waves from the beginning of time
CMB distorted on it's way to us by galaxy clusters
new telescopes are using this to map out the large scale structure and probe the dark energy