I think this deserves own thread.
See this Sky & Telescope article
And nope, it isn't 2003 EL61!
It is less than 3000 km wide, but if it is 100% reflective it must be still bigger than Pluto. It's distance is whopping 97 Astronomical Units and its orbit is highly inclined, 44°. Its magnitude is 18 and is currently in the constellation Cetus.