Yes, Forge is among the many things included in The Master Chief Collection and today, we get our first look at it in action from Halo 2: Anniversary.
The video below is part of IGN‘s coverage of Halo: The Master Chief Collection. Dave Mertz, project lead at developer 343 Industries is walking us through how you can edit existing objects or add yours, just like classic Forge.
There is also an interesting look at a basic scripting system anyone can use when creating maps in Forge. Things like making doors that can be opened by other players etc..