As pointed out by Paul Gilster, beginning tomorrow the robotic spacecraft Rosetta will be maneuvering past the asteroid Steins, which will serve as a reference point for mission control.
Steins is Rosetta’s first nominal scientific target. The spacecraft will rendezvous with the asteroid in the course of its first incursion into the asteroid belt located between the orbits of Mars and Jupiter, while on its way to comet 67/P Churyumov-Gerasimenko.
Beginning in 2014, Rosetta will be the first craft to undertake the long term exploration of a comet at close quarters, and will deliver a lander, called Philae (this image has been my Macbook desktop for a while now), to the comet's surface.
Artist's impression of the comet encounter: ESA, image by AOES Medialab