Updated December 15th, 2015.
Well looky here: another nifty improvement in the Date & Time preference pane, thanks to Snow Leopard! Finally, all of a sudden, and only in Mac OS X 10.6 Snow Leopard, your Mac can show you the correct time for wherever you are– automatically! Those of you who travel with a Mac laptop will appreciate this– no more trips to the Date & Time preference panel to set the proper time zone. You do have to turn this feature on, so get in there and do it now!