After a video release earlier today made it sound like Kathleen Kennedy and George Lucas were just beginning to talk to writers, Lucasfilm has now confirmed that all the rumors about Michael Arndt being the writer are true. Also, pre-production has started. Here's the official release.
"As pre-production of Star Wars: Episode VII begins, Lucasfilm has confirmed that award-winning writer Michael Arndt will write the screenplay for the new Star Wars film. As revealed in the ongoing video series posted here on StarWars.com, Kathleen Kennedy and George Lucas have begun story conferences with Arndt. Arndt won an Academy Award for Best Original Screenplay for writing Little Miss Sunshine (2006), and was nominated for Best Adapted Screenplay for writing Toy Story 3 (2010)."
Star Wars Episode VII is scheduled to be released in theaters sometime in 2015.