Funny this thread is back up. I'm teaching a class on Folklore and just this week I used Planxty, the Waterboys, and a Danish band called Moving Cloud (Irish music from Denmark!) all performing essentially the Prosperous/Christy Moore/John Reilly version of "Raggle-Taggle Gypsies" to show the ways a single version or arrangement of a traditional song can "make the rounds" becoming a standard of the folk revival scene. I also used Thin Lizzy and Metallica (!) doing "Whiskey in the Jar."