Foxflower, thanks for the recipe for the rhubarb slush. Sounds kind of like an Orange Julius (love those, but not often due to calorie counting)!
AnngelAnne, your recipe sounds about like what the restaurant might use for a recipe for the rhubarb lemonade.
I may just scoot on down to the grocery and see if they have any frozen rhubarb. Can't grow it, but I can buy it. The folks on this train sure love to eat, don't they??