According to IGN Filmforce, Nick Cassavetes has been chosen to direct Iron Man for a summer 2006 target release date. Click on the "Film Force" link at the bottom of this post for more details.
His past credits include being co-writer of Blow, the excellent Ted Demme directed movie about the drug trade, and he also directed Denzel Washington in 2002's John Q (which was met with mixed reviews.
Personally I would have liked to have seen a more established director come in on this... but who knows? Maybe he'll do a decent job of bringing my childhood hero to the big screen.
Casting director: You are on notice... do not screw this up.
Source: Film Force