Microsoft has finally extended time zone support to encompass more than just UTC and the user's local time zone. With .NET 3.5/Orcas, .NET applications will be able to fully leverage the time zone information available to the OS. The new type, called TimeZone2, replaces the existing time zone functionality found in the BCL.
On computers running Vista, that includes both future and historic time zone information via the Dynamic Time Zone Information API. On XP only the current time zone information will be available. In order to reduce the chance for a discrepancy between machines, time zone information can be serialized.
For some insight into why the new class was named TimeZone2, see Kathy Kam's web log.