We’ve done some checking of our own and have learned that out of those three names, Baldwin looks most likely to be joining the cast that also includes Will Smith, Tommy Lee Jones, Josh Brolin, Jemaine Clement and Emma Thompson. We’re not sure about Arterton and Copley’s status, but those two are definitely not yet on board.
The site said that Baldwin would play the head of MiB in 1969. Thompson is playing the boss in modern day.
Filming was recently pushed back slightly to November 18 for a May 25, 2012 release in 3D and 2D theaters.
Remember Baldwin’s Super Bowl commercial for Hulu which had a similar "MiB" feel? It seems he would be perfect for the role.