Dust Devils on Mars...

The little Phoenix lander, far in the north on Mars, managed to image a dust devil dancing across the plains. The dust devils were expected; they're a well-known phenomenon on Mars at this point. Spirit and Opportunity (the two rovers that are still operating on Mars) have encountered and photographed them several times. But I don't think anyone was expecting the stationary Phoenix lander to be able to do so. This site has much more information, and an animation.