Actually, there are several of these objects. Google "2010 s016" and you get all sorts of hits. It appears to be one of several objects associated with the primary earth-sun Lagrangian points (not actually orbiting the earth). I'd always heard the Lagrangians were empty, and that an object there would oscillate about them, so this is real news for me. Thanks for turning us on to it.

http://en.wikipedia.org/wiki/2010_SO16

This web page has an animation of the orbit
http://earthsky.org/space/asteroid-2010-so16-is-following-earth-in-its-orbit-around-sun

A properly timed manned mission to this rock should not require a lot of delta-v, it may be our only chance to actually send a chemically powered rocket and human crew to an asteroid and back in a reasonable amount of time.