It seems like there are more beers coming out from Irish whiskey barrels. Anyone know what distillery these guys (hoppin frog, oharas, etc) are using?
I can't answer your question in particular, but I do want to say that Irish whiskey barrels are an interesting choice for beer aging. It seems like a pretty tame liquor compared to bourbon or rye whiskey.
I believe that Innis & Gunn used barrels from the New Midleton Distillery, as it's heavily implied they used Jameson barrels to age their Irish Whiskey Cask Stout. Considering they (the distillery) are so large, it wouldn't surprise me if others did the same.
Ola Dubh uses Highland Park whisky barrels. If you haven't tried one, you should. Really tasty. Pricey as all get out, especially the 30 year version of Ola Dubh, but pretty wonderful.