Small feature with an easy workaround (just enter the flight details closer to the time of travel)...
I have a planned flight coming and have noticed that the time difference shown in the Jet Lag Advisor is the *current* time difference, not the time difference that it will be when I travel.
I live in the UK and travelling to Australia, we have just started BST and Australia also change thier clock at the coming weekend.
The JLA calculates the time difference at the time you enter the details, not at the time of the actual flight.