For anyone using System.TimeZone to provide custom Time zone information, and VS C++ developers using the CRT Time functions:
http://msdn2.microsoft.com/en-us/vstudio/bb264729.aspx
Q: What dates have changed?
A: DST dates in the United States will start three weeks earlier (2:00 A.M. on the second Sunday in March) and will end one week later (2:00 A.M. on the first Sunday in November).
Q: I just use the DST lookup to get the current correct time, do I need to do anything?
A: You will not need to modify your applications because the time zone support in the .NET Framework relies on time zone data provided by the operating system. Time and time zone-aware features of the .NET Framework, such as the System.TimeZone class, will automatically reflect these rule changes provided updates are applied to the operating system.
Q: Which .NET Framework classes are affected?
A: Both System.TimeZone and System.DateTime will automatically reflect these rule changes provided the underlying Windows updates are applied. A new .NET Framework class in Visual Studio code name "Orcas", TimeZone2, will support serialization and deserialization of time zone data and multiple adjustment rules.
More...