Astronomers have found a clump of mud outside Pluto's orbit that is at least as large, and likely even significantly larger than Pluto - Planet or Not, Pluto Now Has Far-Out Rival:
Astronomers announced yesterday that they had found a lump of rock and ice that was larger than Pluto and the farthest known object in the solar system. The discovery will probably rekindle debate over the definition of "planet" and whether Pluto still merits the designation.
Now it's about whether Pluto loses its planet status, or the new one also becomes a planet.