Who is Meyer Wolfsheim, and what do we know of him?

At lunch, Gatsby introduces Carraway to Meyer Wolfsheim, a disreputable character who proudly calls their attention to his cufflinks, which are made from human molars. Wolfsheim is an infamous gambler, and claims responsibility for fixing the 1919 World Series. Nick begins to suspect Gatsby of underworld dealings, due to his association with the sinister Wolfsheim.