Having worked for global financial organisations all my life you accept DST and BST (British Summer Time) changes as a fact of life - you build systems so that they don't fall over or even flinch whenever the time changes locally or in another part of the world. You build systems that carry on working whether the US is 4, 5 or 6 hours behind GMT (I typically use EDT/EST as a basis for US-time as NYC is the financial center for the US).

The time changing in the US a few weeks earlier this year shouldn't affect any reasonably well designed system, as long as all the relevant timezone patches have been applied (where necessary - this change has been know about for quite some time so new installs shouldn't need patching at all).

It's definately worth knowing that the time is changing so the publicity here and everywhere else is a good thing, but it really should turn out to be a total non-event if sys admins have done their job.