I think this is going to end up another Kuiper Belt Object or KBO
Seems like there are a lot of eyes on the Kuiper Belt lately. Other very recent KBO finds...
2004 DW = 1650 km (discovery announced last month)
Quaoar = 1250 km (discovered in 2002)
for what Kuiper Belt is http://www.ifa.hawaii.edu/faculty/jewitt/kb.html