Once again, politicians have thrown us sysadmins a curve. The is is the year when daylight savings time has been extended four weeks (two weeks earlier to start and two weeks later to end). What does this mean? Well, if your computer's operating system was released before the decision was made, your clock will be wrong four about four weeks of the year, unless you live in a place like Arizona where DST doesn't happen. DST for most of the US will be from March 11th to November 4th.
In many datacenters, this is the new Y2K! You won't believe how many devices will not support the new scheme. However, I think it will be the computer users at home that will be affected the most. Microsoft is only supporting Windows XP/sp2 and Windows 2K3 Server/sp1. However, a quick Google search will result in several methods for people to fix their legacy computers.
UNIX systems are quite simple to fix. It has a timezone database that can be quite easy to update. I have some instructions for Solaris here: LINKY
Linux admins can use the same procedure, just find the location of the timezone database and adjust accordingly.
Don't be fooled into thinking that this is all you need to do! The are applications affected as well. Java, compilers, even some firmware in devices like system boards or even RAID controllers might need to be patched. Many applications package their own version of Java (like Matlab) and might not use the latest version with the timezone fixes. If you are just a user and have no clue about your system, call your friendly neighborhood geek and ask.