Okay, so it may not be particularly world-changing in and of itself, but it's still pretty cool: the Mars Rover "Sprit" has captured images of Mars' moons Phobos and Deimos transiting the Sun. When our Moon does that, we call it a solar eclipse. As the photo here shows (click it for the QuickTime movie), the ratio of Martian Moon size to Sun size doesn't result in a real eclipse, but it's the same process.

(Extra bonus coolness: You Are Here -- a photo of Earth as seen from Mars.)