Nikki Finke says the rumors are true:
I've just learned that Eddie Murphy has officially agreed to host the 84th Academy Awards. Today, Oscar producer Brett Ratner is formally telling the Academy Of Motion Picture Arts & Sciences that he's chosen Murphy to emcee the Oscars and an announcement will be made. I broke the news over Labor day weekend that Ratner was in talks with Murphy and was going to offer AMPAS President Tom Sherak only the comedian's name to host. I was told that a lot of big names had approached the other 84th Academy Awards producer Don Mischer saying they are interested in hosting, and Don was fielding those calls. Brett's talks with Murphy had been along the lines of, "If the Academy asked you to host, would you accept?" I learned that Eddie has now formally said yes. This is coming months earlier than normal because usually the Oscars host isn't chosen or announced until January. But everyone is eager to get out the news now.
Read the full story at Deadline.