Update - hopes cruelly dashed. See bottom of post for more.
Eagle eyes have spotted this image on the Double Fine upcoming projects page:
While this is indeed glad tidings for any fan of games possessing character, humour, grand variety and adept storytelling (let's not mention the irksome platforming emphasis during this time of celebration), we don't have any idea what this is. It could be a sequel, it could be a DS or PSP remake, it could just be a graphically-tweaked rerelease to cash in on the original game's ever-swelling cred. But it is more Psychonauts. (Note to self - bloody get around to writing up that bloody Psychonauts retrospective at some point).
Thank you Tim Schafer, thank you.
That said, damn you Tim Schafer, damn you, for making your next game, Brutal Legend, console only. Given it was PC guys that sang Psychonauts' praises the loudest, it's a sad decision.
Update - as has been snootily pointed out in comments, it's since been revealed that the pic's just a teaser for an eventual About page on Psychonauts. The image on the site has been fully-colourised to reflect this. Boo. I would say that Double Fine probably shouldn't have stuck a mysteriously darkened image on a page previously only containing a link to a press release about an upcoming game, however.
(Tinfoil hat)Either that it or it was a secret experiment to gauge interest in another Psychonauts game...(/Tinfoil hat)