This picture was taken by the Mars Reconnaissance Orbiter's HiRISE camera last year from orbit around Mars. Images of the earth from a distance always impress me, and this one is quite a distance: 142 million kilometers! It also does a great job showing the relative sizes and a decent job showing the relative separation (the earth and moon aren't quite aligned perpendicular to the direction of view, so the separation appears smaller than it actually is).
The original source is here:
http://hirise.lpl.arizona.edu/earthmoon.php