According to CNN (which seems to be full of generally crap stories, come to think of it), 2006 was the warmest year on record for the US. Citing the National Climatic Data Center, they stated:
"... the average temperature for the 48 contiguous states last year as 55 degrees Fahrenheit. That's 2.2 degrees warmer than average and 0.07 degree warmer than 1998, the previous warmest year on record."
Additional analysis from arstechnica, citing information from the National Oceanic and Atmospheric administration, says that:
"NOAA blames December's exceptional warmth on an ongoing El Niño event
in the Pacific, which kept Arctic air out of the US. December alone
wouldn't have been enough to set an annual record, however, if 2006
weren't already generally hot—NOAA explicitly blames that heat on
greenhouse gases. Both factors are likely to keep heating up 2007: El
Niño isn't going away immediately, and the generally high temperatures
are part of a trend that now puts 16 of the past 25 years onto the list
of the top 25 warmest years on record."
I don't really have anything to add to this. Except that the U.S. really should have done the right thing and stuck with the Kyoto protocols, and George W. Bush really should have thought about more than just his constituency when he decided to back out of them.