I found this for the State of Wisconsin:
http://www.dor.state.wi.us/pubs/03mf-107.pdf


Disregard my previous enthusiasm. I found the actual refund claim form, and
in the instructions it says: "Refunds may NOT be claimed on fuel purchased
for use in the following vehicles: Snowmobiles, Recreational Motorboats,
All Terrain Vehicles, and Aircraft."

http://www.dor.state.wi.us/forms/excise/mf-023w.pdf

....But.. they still don't require an FBO to charge the fuel tax on
automotive fuel sold on-site to Aircraft. What's up with that?