This is exciting to me!
Today (July 29th, 2005) the discovery of the first planet in the solar system since Pluto was discovered, 75 years ago, was announced. The planet is about 3 times more distant from the sun than Pluto is, and 97 times more distant from the Sun than the Earth is. This 10th planet has a temporary name of 2003 UB313 until a formal name is adopted by the IAU. The size and exact orbit are not yet known, it is however larger than Pluto and up to twice its diameter. This is really exciting to me, it's not every day, or even every century, a new planet in the solar system is discoverd. Because of it's size there is no reason that the IAU shouldn't count this as a planet. It's not quite the mythical Planet X but still pretty damn cool.