Pluto no longer a planet

The Register is reporting that the IAU has (contrary to earlier expectations) decided that Pluto is no longer officially a planet – it’s “dwarf planet”. The decision means that our solar system now has eight planets, and only eight. None of this nonsense earlier of 12, 15, 19 or even more. The decision in full runs as follows – a planet has to orbit the Sun, be round and be the only such body in its neighbourhood. It’s this last qualification that rules Pluto out (because it crosses the orbit of the much-larger planet Neptune).

The IAU therefore resolves that “planets” and other bodies in our Solar System be defined into three distinct categories in the following way:

1) A “planet”¹ is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and© has cleared the neighbourhood around its orbit.
2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape^2^, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
3) All other objects^3^ except satellites orbiting the Sun shall be referred to collectively as “Small Solar-System Bodies”.

^1^The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
^2^An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
^3^These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

Update
Alastair linked to this rather amusing contest :-)