I first caught word of this off of AnimeNation: Yamamoto Yutaka, the director of Haruhi and Lucky Star, will be working with Studio Ordet to produce an original video for Voicaloid's Black Rock Shooter. The project will also have ex-KyoAni staffer Yoshioka Shinobu directing the project, according to Canned Dogs.
While we don't have all the details on the project, some are speculating that this is going to turn into a full-blown OVA or the like. My guess is that it'll be something along the lines of what we see in Guilty Gear: several minutes of animation explaining the story, but that's about it. A big cocktease to the fans.
While we're waiting for the release, you can check out the still images they've got cycling through over on the Black Rock Shooter website. You guys pumped for some fighting and bondage action from Yamakan? Since I don't really know much about BRS beyond the figure, this'll be a good educational piece for me.
An idea of what it might look like
..unless thats what it is