Was listening to The Brewing Network the other day and the guys from Anchor Brewery are distilling as well and had a Hop vodka, they didn't give away much but what i did get was they mashed malted barley and cracked corn, they used more than 1 Americian hop variety. They didn't say where they used the hops but said they had to play around with it quite a few times before they got it right.
Sounds interesting, might have to give it a go.
Any ideas