This is a mixture of a few existing themes, namely the html5boilerplate Wordpress theme and Breakfast, a theme from http://www.opensourcedesign.com/. The idea is not that you would use this theme as-is, but as with html5boilerplate, as a jumping off point for your own theme.
(Largely a copied from Brent Hoover's post to GoogleGroups)
For this packages it's even easier since you actually don't need to install anything. Just drop the contents of the directory you checked out into the root of your project, and add the name of the directory to your INSTALLED_APPS settings.
Clone out mezzanine-html5boilerplate
git clone git://github.com/tvon/mezzanine-html5boilerplate.git
Then just copy the directory out into your project like this:
(Notice the the dash has changed to an underscore, probably a name like "mytheme" might work better)
myprojectroot/
/mezzanine_html5boilerplate/
/templates
/templatetags
/etc...
Then in settings.py change your INSTALLED_APPS so it looks like so:
.....<other_apps_snipped>
"mezzanine.generic",
"mezzanine.blog",
"mezzanine.forms",
"mezzanine.pages",
"mezzanine_html5boilerplate",
Then while you are working on modifying the theme, you will want to add:
THEME="mezzanine_html5boilerplate"
Which allow mezzanine to use the theme without installing it.