Alex...this is actually a pretty complex subject.  Especially since Microsoft did not get it right and had to put put a TimeZone patch for DST.  Microsoft is making adjustments to their TimeZone implementation in the .NET 2007 preview...I have also read several other docs on the web that discuss the issue and possible implementations.  The real issue, I believe, is updating the TZ Tables (in DNN) so that user's have the ability to subscribe and override specific locale TZ rules.  You can't always depend on the server to have the correct TZ information....especially since these are locale specific (i.e. some locales don't observe DST, while others do).  Also, all date/times stored should be translated and stored using UTC +0 and translated to the specific TimeZone, based on the TZ table...this will eliminate confusion and conversion when the rules change (as they did on Microsoft's latest patch).

Done...I hope to get some time and look at what Microsoft is doing for TimeZones in the next .NET Framework release, then help make the mods to the core.  Cheers.