Today Navigation link not setting DayPilotCalendar to the correct date

Yes, you are correct. You should supply the time in UTC (i.e. the time on the client should always be +0000, the time zone will be added on the server).

I know that the UTC trick is a bit confusing (and moreover, the refresh(new Date()) example is not correct exactly as you point out). I would like to get rid of this and handle the time as local time on the client but IE is confusing the calculations by automatically changing to summer time zone in raw operations like Date.setTime() - in contrast to FF. Probably I will create a special wrapping Date class that will hide these problems.

DayPilot always shows the server times (or more precisely, it shows exactly the data from the database because the DateTime database field usually doesn't have the time zone information associated with it).

I'm not sure if there is a way to detect the time zone reliably in the browser (note the IE/FF differences I described above). It would be possible to add options to specify the server time zone (that can be detected automatically as well) and the client time zone (on the server side). You would have to keep the client time zone information in the user profiles and adjust DayPilot settings individually per user.