Thanks for all the complimentary remarks everyone. 
Wow, you guys get raped for material costs down under!
Yes, I'm starting to feel that more and more. There are quite a few things which I can buy 10 of overseas for the price of one here.
I'm storing time zone offsets and DST adjustment rules in EEPROM ...
Well I was tempted, and of course it could be changed. However the government here keeps changing the rules. Something comes up like the Commonwealth Games, and they bring DST forwards or back a week or two.
My ultimate goal would be a heap of clocks that keep reasonably good time, and then a GPS-based "central clock" that gets highly accurate time (eg. daily) and then updates all the other clocks with a radio transmission to them. And that central clock could keep track of daylight savings time as well.