I thought I would revive this thread because SWUs can now be used to upgrade on AF to Premium eco and from Premium eco to Business.

Systemwide Upgrade Certificates redemption on Partners:
Redemptions on Air France
Valid on most transatlantic flights operated by Air France1
One way upgrade from Economy to Premium Voyageur when booked in Y,B or K class
or
One way upgrade from Premium Voyageur to Business when booked in S,A or W class

http://www.delta.com/skymiles/about_...erts/index.jsp

I don't know when that change was implemented but i just discovered it. I thought the premium eco A/W to Business upgrade option with SWU is really nice and is worth getting the message out there