I just attended a fantastic, standing room only SXSW panel titled "Why Social Ads Work. Ignore Facebook Naysayers" with Kurt Abrahamson, the CEO of ShareThis, and Brandon Rhoten, the Director of Digital Marketing for the Wendy's restaurant chain. Both Kurt and Brandon spoke very openly about digital advertising, and social ads in particular.
Wendy's is a $9 billion company with over 7,000 locations in US & Canada (although only 150 locations in CA). Its biggest competitors are other QSRs (Quick Service Restaurants) like McDonalds and Burger King, but Wendy's is more interested in what newer chains like Chipotle are doing than these more traditional competitors, since Wendy's biggest business challenge is to have 20 and 30 somethings choose Wendy's over chains like Chipotle (Wendy's does very well with the older demographic, though, since it's a 60+ year old brand). The entire QSR industry is a $519 billion industry.
Here's the video of the event (sorry for the poor video quality; I was barely able to squeeze into the room)