The IAU has released the official names for the dwarf planet that caused Pluto's downfall: Eris (who in mythology caused a quarrel among the goddesses that lead to the Trojan War. Who says scientists don't have a wry sense of humor?). Eris's large moon is Dysnomia, the daughter of Eris and the spirit of lawlessness (sounds like Bush).
See the IAU resolutions here, or perhaps more the readable BBC news article here.
OK, that's enough blogging about planets for a while.
[Update 07/26/2016: Latest figure show Plut to be slightly larger but Eris to still be more massive]
|Mean radius||1163±6 km|