Personally I would consider an object with an atmosphere that orbits the sun a planet. Moons would still be moons because they orbit planets.
Three moons, round with an atmosphere- Mercury only has one of those qualities. Any change in status for Pluto should have been put off until the arrival of the New Horizons space probe- then astonomers would be better equipped to make a decision as to what Pluto really is.
I am glad they didn't upgrade Charon to "dwarf planet" as had been discussed. That would have requried upgrades for the Moon, Io, Europa, Callisto, Ganameade, Titan and Triton as well.