Apparently it's in the works. Notable quote:
In what may become big news for both the grappling and MMA world is an announcement that came Friday evening from DEEP. They are in negotiations to have ADCC champion and submission wizard Marcelo Garcia to take on the equally impressive Shinya Aoki at their DEEP X 2007 event on June 17. These two met in a grappling match in the 2005 ADCC Submission Wrestling World Championships, where Garcia won by rear-naked choke in less than two minutes.Aoki has got to have significantly better stand-up and he's also the type of fighter to look at this fight as an opportunity to redeem himself. In many respects, this would be a real test for Marcelo since not only is Aoki likely the superior striker, but also because Aoki has more experience grappling in MMA situations. Learning how to apply a submission from the guard while an opponent is swinging at you requires poise, toughness, and different technical applications than pure sport BJJ.
Still, though, this would be an amazing fight: (arguably) the best grappler in the world versus (arguably) the best MMA grappler in the game. Fireworks, my friends. Fireworks.