As Rosetta crosses the last couple million kilometers separating it from its target comet, the spacecraft is snapping away with its OSIRIS camera. They take these images primarily for optical navigation -- to help steer toward the destination. But the photos have also caught the comet beginning to act like a comet, throwing off gas and dust to develop a coma that is already 1300 kilometers across, and growing. All this from a nucleus only 4 kilometers across.
Here's a zoomed-in look at the comet on April 30:
Rosetta is now matching paces with the comet. The next rocket maneuver, a very large one, is planned for May 21. More information on ESA's website!