A 10th planet has been detected, and at 3,000 km across it's smaller than Neptune but larger than Pluto. Alas, it has a rather dull designation
2003 UB313. For a name, I hearby propose it be known as the Hangul syllable "daes," one of the Han symbols used in Korean (I have no idea how it's pronounced, but when we find out, that's how we should say the planet name), which corresponds to the Unicode character U+B313 [see the glyph; or in a large pdf lookup chart].
Refs: the Unicode book, chapter 10, on East Asian scripts [pdf] and the Unicode Checker application [via the 2lmc spool], which I heartily recommend to planetismal-discovering astronomers as a useful, extensible naming device when UB314, UB315, and so on, need to be called something.