While investigating bugs, I found one for Apple today. Either this has bit a lot of international travellers, or nobody has noticed it because you usually turn your menu bar clock on (or off) and never touch that setting again. Or everybody turns their menu bar clock on BEFORE changing the time zone - if you do that the clock is correctly updated.

So, check this out:

Here's how to reproduce it:

1. Turn off your menu bar clock (if you have it turned on)
2. From the Date & Time System Preference, change your time zone (I'm on the East Coast, so I set my time zone to somewhere in Central Europe Standard Time by clicking on eastern Europe on the map)
3. From the Clock tab of the Date & Time pane, turn on the menu bar clock
4. Switch back to the Date & Time tab
5. Notice the correct time in the Date & Time Tab, and the incorrect time in the menu bar Clock

rdar://problem/4311046