Yup, officially they're only good on the date posted, but the CMs have been instructed to take them regardless of the date. We just used some last week that our friends had won in August, the day they were leaving, and they weren't able to use but a couple of tabs. We never had a problem.
I guess the idea is, that sometimes they have been handed out on slow days when FPs aren't needed on most of the rides. If ToT is walk-on, who needs a Dream FP? Also, sometimes people win them when they're literally on the way out of the park on their last morning before an early afternoon flight out. When would you use them? So with that logic, they're now taking them until the end of the Year of a Million Dreams, January 1st, 2009.