Yes, I'm afraid its true, the time zone offset is just a straight hours offset from GMT, it does not auto adjust according to Daylight Savings so it would ahve to be adjusted manually as needed.
Daylight Savings time is a very complicated thing, its different in various time zones and, even more complicated, some regions a person may be in one time zone part of the year and another time zone other parts of the year. In .NET 1.1 and 2.0 there was not much built in to help with this, but maybe there are some new things in .NET 3.5. When I get a chance I will investigate whether there is anything new that may help us support automatic adjustment for Daylight savings time.
Best,
Joe