It was a tradition on Australian comedy show The Money Or The Gun that musical guests finish each show with a cover version of Stairway to Heaven in their trademark style. There was even a sea shanty version, and this is how Rolf Harris came to cover it, and dozens more - but not Dolly Parton. See:

http://www.amazon.com/Stairways-Heaven-The-Money-Gun/dp/B000BJTJE8