New Scientist is carrying this summary of a startling new discovery about the most distant objects in our solar system, Kuiper belt objects. By using the 8-meter Subaru (no, really) telescope in Hawaii, scientists have observed evidence of crystaline water and possibly ammonia on the surface of Quaoar, the largest-known object in the Kuiper belt.
What makes this remarkable is that Quaoar isn't close enough to the sun for water to get warm enough to actually crystalize. The heat has to be coming from somewhere else, the most likely candidate being heat from radioactive decay. Seems that the furthest reaches of the solar system aren't quite as cold and dead as they once seemed.