Turns out we needn't worry about the use of the word "pluton" afterall. The IAU general assembly passed the following resolution:

RESOLUTIONS
Resolution 5A is the principal definition for the IAU usage of "planet" and related terms.
Br> Resolution 6A creates for IAU usage a new class of objects, for which Pluto is the prototype. The IAU will set up a process to name these objects.

IAU Resolution: Definition of a Planet in the Solar System Contemporary observations are changing our understanding of planetary systems, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation 'planets'. The word 'planet' originally described 'wanderers' that were known only as moving lights in the sky. Recent discoveries lead us to create a new definition, which we can make using currently available scientific information.

RESOLUTION 5A
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" 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 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".

IAU Resolution: Pluto

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.

The resolution comes with a footnote that (a) The eight planets are: Mercury, Venus, Earth, Mar, Jupiter, Saturn, Uranus, and Neptune (b) Ceres, Pluto, and 2003 UB313 are the first three "dwarf planets", while additional ones would be under review by the IAU (c) Everything else pretty much all fall under the category of "small solar-system bodies".

So, yes, it is official, Pluto has been demoted. A word on its demotion, however: I strongly doubt that Pluto has been demoted because of the reason given by popular press accounts of the event (which even made its way into Wikipedia). They claim that

Pluto is demoted because its orbit intersects with that of Neptune, and thus fails the 3rd criterion of planethood.

In my opinion, that is just nonsense. If that were the case, they might as well also apply the same reasoning to Neptune and demote it at the same time. I think a better reason (more likely the one that the IAU actualy used) is the fact that Pluto is smack in the middle of the Kuiper Belt. The Kuiper Belt is a region of space between 30 and 50 astronomical units (1 AU is roughly the distance from Earth to the Sun) from the Sun, just outside the orbit of Neptune (at 30.07 AU). Objects in the belt are thought to be minor objects that, during the formation phase of the solar system, were affected by Neptune: they are either swept up by Neptune (possibly captured as a moon) or are gravitationally pushed away (through some sort of slingshot action similar to how the Apollo 13 astronauts managed to get home). So Neptune clearly cleared a path around its orbit (it absorbed those KBOs that came too near, and bounced others away).

Pluto, which orbits at 39.48 AU, didn't. Here is a picture of the distribution of objects in the Kuiper Belt. At 39 AU from the sun, there is a huge cluster of objects: they are the plutinos, which has a 2:3 resonance with Neptune. Just outside of the plutino group, you find the cubewanos, which are the majority of Kuiper Belto objects. They do not resonate with Neptune. This density of objects around Pluto, I think, is the real excuse for not including Pluto as one of the planets. (The same reason also explains why 2003 UB 313, another KBO, and Ceres, the largest object in the asteroid belt, cannot be put as planets: they have too many neighbors!)