As much as I might be both pleased and terrified to claim responsible for this picture of the crescent Earth, I actually found the image here, at the European Space Agency's site dealing with the Rosetta probe (official page here.) Rosetta, scheduled to rendezvous with the comet 67P/Churyumov-Gerasimenko in 2014, made its final gravity-assist approach to Earth this month, coming closest on the 12th. Just before the Earth's gravity swung it out in space towards said comet, at a distance of 630 thousand kilometres Rosetta took a picture.
I found this photo via Phil Plait's Bad Astronomy blog.
