Taken from internet at http://www.iwight.com/home/latest_news/concessionary_fares/default.asp

Area and times of permitted free Travel
The area of travel will be the Isle of Wight at any time of the day, any day of the week, subject to local bus operating times.

We have also been informed that concessions are available on Southern Vectis buses in the Isle of Wight at all times on all days, including the various "Breezer" open-top services. We have been informed that you cannot use your concessionary pass on the Road Trains.