I recently bought an "atomic" radio receiver watch... It synchronizes itself every nigh from the atomic clocks owned by the National Institute of Standards and Technology near Ft. Collins Colorado. The NIST has a low frequency transmitter that constantly sends a synchronizing signal that these special watches and clocks use.
I never have to set the watch. It's always within 1/100 of a second of 'official time'. I got up this morning and the watch had set itself to DST. Of course, I had to set all the other clocks in the house.
Here's a writeup on how these atomic watches/clocks work:
Information about WWVB Radio Controlled Clocks