According to Variety, it's real. Steven Spielberg has tapped Diablo Cody (Juno) to pen a screenplay for a comedy, the idea for which was apparently an original one from Spielberg himself.
The most interesting part of the story to me is that Spielberg saw the screenplay for Juno when Mandate Pictures was looking for a domestic distributor, and even more importantly, considered directing it.
I kind of wish that had happened, somehow, at least at this very moment (literally about 90 seconds after reading the story). It would have been different for Spielberg, and I'm confident he would have brought more to the plate than Jason Reitman, though I must give Reitman a great deal of credit for extracting some memorably solid performances and for making what was a fairly incondite screenplay into something at least marginally better.
Anyway, Variety tells the tale: