If you click the link in my signature and look at our "Sept. 2006" pictures, there are a few pictures from this event. They let you go in, get your child settled, snap a few pictures, and then they throw you out.
It was the absolute highlight of the trip for my son, who was 3.5 at the time. (They used to take 3 year olds, but upped the age requirement to 4 about a year ago to bring it in line with the other children's programs.)
They had little sandwhiches, fruit, tea (was really apple juice), and they got to decorate their own cupcakes.
My son had a blast playing with Alice and the Mad Hatter, but the draw for him was really getting to play with other kids.
I used the time to shop at the Grand Floridian and explore the grounds, so we both had a nice time. I'd highly reccomend it.
He did the Pirate Adventure Cruise on our trip last month, and loved that was well. Both of these events are so much fun - as long as your child is the type that doesn't mind being separated from mom or dad in a place where they don't know anyone. My son didn't mind at all (and I knew he wouldn't), but I did see several clinging, scared, crying kids at both events that just didn't want to be left behind.