The last time the European Space Agency tried to drop something onto a planet, the Beagle 2 was lost, and no one was able to determine why. This time, the Cassini orbiter has dropped Huygens onto the surface of Titan, Saturn’s largest moon and one of the few atmosphered bodies in the solar system. If everything is going according to plan, Huygens should have hit the ground about an hour ago, and NASA will begin recieving data (relayed through Cassini) around 10:30 EST.
Update: "European Space Agency mission managers for the Huygens probe confirm that data of the probe's descent to Saturn's moon Titan are being received." "The Huygens team ... hope to release first images later today." Great news!