This is an Octopress theme used on my personal blog. Some elements of this theme are based on the "dark-stripes" Octopress theme by Alessandro Melandri.
Change into the directory where your octopress installation resides and add it as a submodule:
$ git submodule add git://github.com/temikus/denim-theme.git .themes/denim
$ rake install\['denim'\]
$ rake generate