Keller Williams is the king of the whole looping thing if you ask me. I don't particularly care for his music, but he simulates an entire band using looping and it's pretty impressive. His technical setup is pretty insane. Here's a link to his page :
http://www.kellerwilliams.net/intern...tion.gear.html
The looping thing has gotten bigger because it's really easy to do and makes your typical solo singer-songwriter thing more interesting/entertaining. I think people think it's harder than it actually is.