I'm getting in late on this forum, but I just heard Mary Black's version on LiveIreland.com, and I thought I'd see what I could find on the web about it. I first heard the song about a year and a half ago, done by Gallowglass, a group from Las Cruces, New Mexico, of all places, and I found it very haunting. Then when I saw "The Gangs of New York," I recognized it in the soudtrack as Leo is watching the Irish men being loaded off a ship and having a gun shoved in their hands. Chilling. You can order the Callowglass version at: http://www.nastycactusmusic.com/gallowcd.htm
Their style ranges from haunting to hilarious, and no, I don't have any connection with them.