There is a commercial maple wine made and available here in Nova Scotia
(probably available throughout Canada), which is made by Jost
Vineyards. You can find a description of it at
http://www.jostwine.com/selection.html

Apparently, it's made with maple syrup and fresh maple sap. I've tried
it, and it is a very nice dessert wine. It is very sweet, and the
maple flavour definitely shines through.

Jesse