Based on an email I got from Filias and the translations from Polish, it looks like Quentin Tarantino is going to be appearing in a Japanese western film by Takashi Miike called Sukiyaki Western: Django. The film will be set in Japan during the 1100's and will be shot entirely in English.

Some details in English from Ryuganji.net:

Miike travelled to the U.S. to ask Quentin Tarantino to appear in the film. "He's a guy who doesn't play by Hollywood rules, so I thought he'd suit this film. I was in his Hostel too". The Kill Bill director will arrive in Japan later this month and film his part at a studio in Tokyo. He plays a mysterious dude by the name of Ringo who appears at the beginning of the movie and fights with an unnamed Japanese cast member, who plays the lover of a female assassin disguised as a town dweller, to be portrayed by Momoi Kaori. "In the States he's not acting anymore, but he said he'd take this film seriously and is preparing for the role."

There have also been some storyboards from the film posted online - but it doesn't reveal much of the story. The film is scheduled for an August 2007 release in Japan.

If the name hasn't clicked for you yet, Takashi Miike is most famous for Ichi The Killer.