I understand that the whole purpose of torturing Han (and Leia?) was to lure Luke to Bespin, but I also heard that there was more footage that was cut from the film before its initial release. Does anyone know if it was ever released as extra footage, or what happened?
As Richard links to, some extra footage was filmed, but then cut.
In Laurent Bouzereau's book, Star Wars: The Annotated Screenplays, director Irvin Kershner speaks of the edited torture scene:
"I originally filmed more shots of Solo as he is being tortured. There were flashes of electricity everywhere. But it was cut out because we were afraid it might be too intense for children. We also took out some of his screaming offscreen when Vader is talking to Lando outside the cell."
There is no substantial changes, as what was cut did not change the scene or plot in any way.