Robert A. Heinlein: In Dialogue with His Century Volume 2: The Man Who Learned Better by William Patterson, Jr. is scheduled for publication June 2014.
Advance copies are already in the hands of people it’s hoped will write a nice blurb. You lucky dogs!
It’s available for preorder from Amazon now. (I’d link Tor or Macmillan, too, if their sites were taking preorders.)