The story follows a fundamentally sweet, mild-mannered proofreader at LIFE magazine who creates elaborate fantasies in which he is the dashing, adventurous hero he's incapable of being in his actual life.  Stiller is set to star as Mitty, a role originally played to perfection by Danny Kaye.  Kristen Wiig is set to play the female lead, with the great Shirley MacLaine playing Mitty's mother.  Patton Oswalt is also set to appear as a representative of a dating site who helps Mitty create an online profile.

According to Deadline, Scott is in final negotiations to appear in the film, but the nature of his role is completely unknown at the moment.  As demonstrated by his outstanding weekly work on NBC's Parks and Recreation, Scott could be playing some friendly supporting character.  Considering the ease with which he played a raging douchebag in Step Brothers, though, he could just as well be playing a nemesis for Mitty, perhaps a competitor for Wiig's affections.
Scott's a proven commodity with a perfect sense of comedic timing and an outstanding ear for deadpan delivery.

Aside from playing Ben Wyatt on Parks and Rec, Scott will next play a lead in Friends With Kids, a comedic drama in which Wiig plays a supporting role.  He also turns up in See Girl Run and My Mother's Curse, as well as the comedy A.C.O.D., which begins production in Atlanta next month.  Hopefully we'll once again see him sporting a pink bowtie when/if the Party Down movie comes together, at which point the only relevant question will be, "Are we having fun yet?"