A few years ago I had posted what I "THOUGHT" was a method to resolve the TimeZone issue that many of us struggle with but it turned out that not only was I completly wrong, but I was actually barking up the wrong tree!
TimeZone configuration can be a major headache when your enterprise spans multiple timezones, or multiple countries, if you are trying to keep your imaging strategy basic and easy to maintain. I'm not a huge fan of splitting imaging into numerous collections with each collection given their own Task Sequence Variable to identify TimeZone since that just takes too much work, and I'm lazy! Up until now I have been just dealing with imaging in one TimeZone then manually adjusting based on the region, totally not efficient!
I came across this excellent blog post which explains it quite well:
Basically, rather than rely on a TS Variable, instead use a VB Script at the end of your Task Sequence that will automatically adjust the timezone based on the DHCP server it is connecting too. As the blog states, the account used to run this script needs to have read rights to the registry on the DHCP server, but it works qutie beautifully.
Check it out!