After visiting Vesta for months on its way out in 2012, the Dawn spacecraft is approaching Ceres. It will spiral in towards the asteroid/mini planet during March, and reach a close orbit (375 km) and return visible and IR imagery and gamma ray data starting in April.
This exploration is a groundbreaking use of an ion drive, which has enabled unprecedented periods of (low) thrust, many years worth. It also made it possible to reach Vesta, maneuver into orbit, and then depart orbit and reach Ceres, where it will orbit. All on one voyage!
These planetary missions share several very impressive features. They are long time scales (a decade and more), which require the spacecraft to hibernate for long times and then wake up. In deep, deep cold, far, far from home. Awesome!
And they are semi-autonomous systems, working beyond any hope of human assistance. The fact that the software actually still works in this situation is just plain miraculous.