Marvel made the announcement today though they have not revealed what Freeman's role will be. There is some speculation out there that it will be a government role and that Freeman will appear in more than one Marvel film.
"From his roles as Bilbo Baggins and Doctor Watson to Tim in 'The Office,' Martin's range from the dramatic to the comedic has consistently impressed us," said the film's producer and Marvel boss Kevin Feige. "We couldn't be more honored or excited to have such a talented actor join the Marvel Cinematic Universe."
Even if Freeman turns out to be another Agent Coulson is that really a bad thing? His grasp of dry British whit would be welcome to the comedy and action mix that is a Marvel superhero film.