The project, which is tentatively titled More As The Story Develops, will focus on cable news anchor Will McCallister (Jeff Daniels) and his crew.
According to Deadline, Pill is in talks to play Maggie, an associate producer on McCallister's show, while Munn will play a financial analyst who works on the same network.
Pill previously starred in 2010 film Scott Pilgrim vs. the World, and also appeared in the second season of HBO drama In Treatment. Her other television credits include roles in CSI, Law & Order: Criminal Intent and fantasy mini-series The Pillars of the Earth.
Munn most recently featured as a series regular on NBC sitcom Perfect Couples and has also made acting appearances in episodes of Chuck and ABC Family's Greek. She has also worked as a television host on The Daily Show and G4's Attack of the Show!.
It was recently reported that Marisa Tomei is close to signing up for the Sorkin pilot, which will be helmed by Greg Mottola.
Sorkin previously described More As The Story Develops as "aspirational" and admitted that he is "loving the idea of coming back to television".
> Read Digital Spy's pick of the pilots