As promised, the MESSENGER spacecraft has produced its first picture from orbit
Of course, the big difference is that the Moon was formed from the remnants of a massive collision between the proto-Earth and a large Mars-sized impactor 4.5 billion years ago.
There is some evidence of flood vulcanism on Mercury, especially the Caloris Basin, which appears to be the result of an empact on the opposite side of Mercury, where the shockwave travelled all of the way around the planet to concentrate the energy and melt the crust.
See this image and click to see the high resolution image mosaic of Mercury taken while MESSENGER was still in solar orbit.
There’s lots more high resolution imagery to come from MESSENGER, and I’m sure a few more surprises and puzzles to come as well.