http://gigaom.com/2010/04/22/facebooks-instant-personalizati...
Old instructions on how to turn it off, back when it was simple:
http://gadgetwise.blogs.nytimes.com/2010/04/23/how-to-opt-ou...
But of course, facebook doesn't want you to turn it off so they made it a few clicks:
http://www.youtube.com/watch?v=j0Ei3HNeQkc