Thanks for that, Dani. For an astrophysics geek like me this is a huge deal and that post was beautifully clear and eloquent. I imagine there are some very excited cosmologists right now.

wait, i thought that the background radiation is not actually completely even, and that in some areas there is up to 10% difference from the average.

The background radiation has fluctuations, but until the data from WMAP came out, these fluctuations were thought to be consistent with a nearly-scale invariant Gaussian distribution.

In general, however, the background radiation is pretty smooth -- smooth enough that before WMAP the larger fluctuations were essentially unknown.