Hi! I'm not sure about medicare covering this, but there is a forum on OH just for insurance questions. http://www.obesityhelp.com/forums/insurance/ Maybe you will get more answers if you post there too, but someone here might know. Good luck to your friend!
Interestingly, yes medicare and medicaid will pay for it and some other insurances won't.
Also interesting to note...obesity is looked at as a public health problem AND doctors and people in public health are now looking at WLS as the appropriate pathway to combat obesity.