[time-nuts] Time Zone correction from GPS data?

[lists at lazygranch.com]

Arizona is the prime example of time zone confusion. The state remains on standard time all year, but the Indians get to pick if they want to go on daylight savings time. 

The "West Wing" did a whole episode around time zone confusion, but I believe it was in Indiana. 

Cell phones are probably the best for detecting time zone change though all the phones I've owned let you choose if you want to change zones.  I assume they get the time zone from the tower.