Well, the combined might of astronomy's best eggheads have got together and decided that Pluto is no longer a planet. This means that a truth that you have all grown up with, that the solar system has nine planets, is now incorrect. Pub quiz goers should probably revise the new formation.
The commitee rejected a previous proposal to enlarge the solar system by three to include the more exotic outer system objects like Charon or 2003 UB313.
So this new classification leaves Pluto out of the planet-club, and lumped together with other Kuiper-belt objects as the rather nondescript sounding "trans-neptunians". Personally, I'm a little bewildered at this decision, as it seems to serve no purpose. Firstly, if you're going to classify things based on arbitrary cutoffs, why not do it in such a way as to not render school textbooks wrong. Why not say: "a planet is defined as a body orbiting a star with a diameter greater than x kms at a distance less than y AUs", where x and y are Pluto's properties.
Secondly, the term planet is so utterly nebulous anyway that it serves no scientific purpose. Why are pluto and mercury morphologically different, but mercury and jupiter morphologically similar? Oh, we've now got the "Terrestrial, Jovian and Dwarf" sub-classification, so why not make Pluto a dwarf?
Mind you, if nothing else, this will really fuck with the mind of astrologers!