While conducting research for a now-cancelled documentary on the making of 2001: A Space Odyssey, Warner Brothers found 17 minutes of "lost footage" from the film, perfectly preserved in a Kansas salt mine. According to reports, 2001 sfx supervisor Douglas Trumbull mentioned the footage in a Toronto presentation last week. Apparently, Stanley Kubrick cut out approximately this amount of the film shortly after it was premiered. According to a post in this online forum by someone who was at Trumbull's lecture, those are the scenes that were found in the storage facility. From IMDB:
The film originally premiered at 160 minutes. After the premiere, director 'Stanley Kubrick' removed about 19 minutes' worth of scenes and made a few changes:"Douglas Trumbull in Toronto" (Eagle Transporter Forum, via @ChrisCarter)
• Some shots from the "Dawn of Man" sequence were removed 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 were removed.
• An entire sequence of several shots in which Dave Bowman searches for the replacement antenna part in storage was removed.
• A scene where HAL severs radio communication between the "Discovery" and Poole's pod before killing him was removed. 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 were removed.