It is in production.
Links to more information.
Quint on the set of THE MIST: Day 1!!! -- Ain't It Cool News: The best in movie, TV, DVD, and comic book news. The Mist (2007)
The cast as I understand it is...
David (Thomas Jane) – The lead character, everyman type. He’s a Drew Struzan-like poster artist.
Billy (Nathan Gamble) – The kid from BABEL plays David’s young son.
Amanda (Laurie Holden) – Pretty girl in the market. There’s a chemistry between her and David.
Norton (Andre Braugher) – David’s dickish next door neighbor.
Irene (Frances Sternhagen) – The sweet old lady from MISERY plays this character, a school teacher.
Ollie (Toby Jones) – Like I said before, Ollie’ll be an audience favorite. He’s a manager at the store.
Mrs. Carmody (Marcia Gay Harden) – Creepy religious zealot.
Sally (Alexa Davalos) – Check-out girl. There might be something between her and…
Jessup (Sam Witwer) – A young army man who enters the store, about to go on leave.
Jim (William Sadler) – A mechanic.
Norm (Chris Owen) – The bagboy who doesn’t have a good day.