From this piece in the UK Guardian, in the final paragraph, comes this quote:

Michelle Williams, who was nominated for an Oscar for her turn as a betrayed wife in Brokeback Mountain, will appear in Spike Jonze's next film, Where the Wild Things Are, about the imaginary world of a mischievous little boy. Next summer, she will also star in the as-yet untitled directorial debut of screenwriter Charlie Kaufman, who worked with Jonze with great success on Being John Malkovich and Adaptation.

Well now. There are a few things going on in this paragraph. I hardly need to point them out. But I'll extend my index finger toward two things. 1. I'd take “next summer” with a grain of salt, since Charlie's films usually spend a lot of time in the editing room — and since we've heard basically nothing about the film's progress until now. 2. “directorial debut of Charlie Kaufman”? Is this still the untitled horror flick that Spike was originally meant to direct? If true, colour me excited.

Despite the Guardian being a fairly reliable source, I'd take all of that with generous doses of salt until we hear more.