And check out the Hadley Rille Books website for their latest call for submissions - a new anthology called Footprints, also with a lunar theme:
Long after our species and all its works have turned to dust, the moon landing sites will still show evidence of our time here on Earth. Imagine future explorers from among the stars interpreting that. The astronauts’ footprints should last longer than the fossils in the Olduvai Gorge have.
The story I already have that fits the theme is far too short, but I think I've another idea brewing. :-)