So its official, Pluto is no longer a planet. Well that isn't exactly true either, it is a dwrarf planet, not a classical planet like the other 8. It falls under the umbrella of being a planet but it isn't really.
Now I grew up with people teaching that Pluto was a planet, but we all knew all along that it wasn't really. It is much smaller than the other planets, it doesn't really fit in where it is. Jupiter through Neptune are "Gas Giants" and pluto is this little rock smaller than our moon. Even if you ignore that you can't ignore its orbit. Which is off the plane of the other planets and even brings it in closer than Neptune sometimes. This really doesn't seem like a planet.
I am kind of sad to see it loose its planet status though, I think it should have been grandfathered in as a planet since it has been considered one since the 1930's when it was discovered. It just doesn't seem right to take that way from Pluto now.
CNN has a pretty good story about the whole situation here
I was a little dissapointed that they did not rename Pluto as a double planet with its moon. Charon is about half the size of Pluto but it is large enough that they actually orbit a point in space between each other. I thought it would have been pretty cool to have a double planet system in our solar system but it was not to be.
If you want more information wikipedia has a great article on Pluto and its moons.
Oh and incase anyone is wondering, Pluto is not named after a cartoon dog. Pluto is the Roman god of the underworld.