This is a pademelon — the smallest of the macropods. Macropods, of course, are all the kangaroo-like mammals in Australia, including wallabies, tree kangaroos and the regular old kangaroo kangaroos. A full grown pademelon stands just about two feet tall.
Nikon D200 with Nikkor 600mm f/5.6 manual focus lens, ISO 200, f/5.6 at 1/40th of a second