The Basic Plot in Five Words or Less: Explanation of nine years previous.
My Basic Ramblings: After being completely dumbfounded by 2001, Chris discovered, lo and behold, he had a copy of 2010 on video. (The tape was about twelve years old, and people sounded like they were under water some of the time, but it was still watchable.) So we watched it.
I got the impression that the general attitude of the movie was "Look, we're real sorry that 2001 was so hard to understand. We'll speed things up this time, and try to explain everything." Not that this is necessarily a bad thing.
We learn that HAL (who, thankfully, is voiced again by Douglas Rain. I was worried they'd try to foist a new voice upon us [ "foist" is a great word, isn't it?]) broke down aboard Discovery because he was asked to lie to Frank and Dave about the nature of the mission. I suppose it's heartening to learn that an advanced computer system doesn't have the ability to lie programmed into it, that it's a sign of hope for the future, but there's be more people alive if someone had told HAL "Look. People lie. It's a fact of nature. It may suck, but there's really nothing that can be done to change it. Lie and get over it."
Roy Schneider, of Jaws fame, takes over as Dr. Haywood Floyd. I wonder if his middle name is "Jablowme". (Actually, I don't wonder, but I thought it should be said.) He and John Lithgow (who was born in Rochester) and the guy who plays Dr. Chandra go aboard a Russian spacecraft run by Helen Mirren to go check out Discovery, which is still in orbit around Jupiter. Why the Russians are interested in Discovery I don't know, I came into the movie about 15 minutes late. Anyway, Russia and the US (headed by President Arthur C.Clarke and Premier Stanley Kubrick - watch the scene where the nurse reads Time Magazine and you'll see what I mean) are on the verge of war and it's not really a smart idea for the Ruskies and the Americans to be on the same ship.
Anyway, they find the Discovery and Chandra re-boots up HAL and Dave Bowman keeps appearing (Keir Dullea in a role that gives him a Kevin Bacon Number of 2) alternating between being young and old and Jim Henson's Star Babies. (And they keep mentioning that the events of 2001 happened "nine years ago", as if the average moviegoer couldn't subtract 2001 from 2010.) Jupiter is revealed to be a breeding ground for monoliths, and eventually it explodes into a new star.
Wouldn't a second sun so close to the Earth really mess with the climate? Would the new JupiterSun pull Earth away from its orbit from OriginalSun? At the end of the film, Floyd talks about (in voice-over) how there's never darkness anymore. What about all the poor nocturnal animals? Bats and things like that? They'll die! Children of the future won't understand the concept of Batman! This is a serious problem that is not addressed in this film.
Little Trivia Bitlets: Besides the fact that Arthur C. Clarke and Stanley Kubrick appear on the cover of the nurse's magazine, the voice of SAL 9000 (at the beginning) is Candace Bergen, under the pseudonym "Olga Malsnerd".