Ceres, dwarf planet

As widely reported, on 24 August 2006 the IAU defined planets and other bodies in our Solar System into three distinct categories. The resolution reads in part:

(1) A 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, and (c) 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, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Under the new definition Ceres becomes one of three "dwarf planets", the others being Pluto and the yet to be named 2003UB313 ("Xena"). Lost in the shuffle seemingly is the possibility of double planets. As I read it, the definition applies only to our Solar System and thus totally sidesteps the question of exo-planets and rogue planets.