According the 2001 IMDB page, when the film premiered in 1968, it ran 160 minutes. Kubrick then went in and trimmed a good 19 minutes or so. It’s assumed this would be the footage that was found in Kansas. Here’s what the IMDB says was cut:
Some shots from the “Dawn of Man” sequence and a new scene was inserted where an ape pauses with the bone it is about to use as a tool. The new scene was a low-angle shot of the monolith, done in order to portray and clarify the connection between the man-ape using the tool and the monolith.
Some shots of Frank Poole jogging in the centrifuge.
An entire sequence of several shots in which Dave Bowman searches for the replacement antenna part in storage.
A scene where HAL severs radio communication between the “Discovery” and Poole’s pod before killing him. This scene explains a line that stayed in the film in which Bowman addresses HAL on the subject.
Some shots of Poole’s space walk before he is killed.
While none of that sounds particularly exciting, new Kubrick is new Kubrick and it would be pretty cool for this footage to make its way onto some sort of epic, mega Blu-ray release one day. Still, I don’t know if I’d want to see it edited into the film. Kubrick cut it, why would anyone want to go against his wishes?
Surely this would fall under “deleted scenes”. (Also, next year is the 50th anniversary of the movie…somehow I doubt this discovery is a coincidence.)