In addition to the ABC shutout stories, apparently the president of the Academy's term change played a role. Tom Sherak was reportedly negotiating with Fallon and for Lorne Michaels to produce the Oscar telecast. Michaels is of course SNL's famed creator and producer as well as producer to Late Night with Jimmy Fallon, Late Night with Conan O'Brien before it, and 30 Rock, Portlandia and Up All Night. Sherek commented today that the Academy's Board of Governors gave him the authority two months ago to find a producer for the 2013 show but he was not able to complete a deal before his term as president was up.
Main sources for info: LA Times article from 6 days ago that was updated today and the Today Show interview between Matt Lauer and Jimmy Fallon.