If you pay much attention to many other space/astro news sites or blogs then you most likely already know that NASA's MESSENGER craft has recently flown by Mercury and taken the first ever pictures of one of its hemispheres.
When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter. As a consequence, Mariner 10 was able to image less than half the planet. Planetary scientists have wondered for more than 30 years about what spacecraft images might reveal about the hemisphere of Mercury that Mariner 10 never viewed.
The MESSENGER probe flew closer to the first rock from the sun than any previous man-made craft, around 124 miles from its surface. The image on the right was taken at a distance of about 17,000 miles, about 80 minutes after MESSENGER's closest approach to the planet, using a filter sensitive to light near the red end of the visible spectrum. NASA has also said that more pictures will be on the way, so as soon as I get them I will put them up.
Image: Mercury, hidden hemisphere. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
More Info: MESSENGER homepage
Picture Perfect Little Mercury
The Side Nobody has Seen