Clone the repository and install some gem dependencies:
git clone git://github.com/fnichol/iterative_chef.git
cd iterative_chef
bundle install
gem install chef
Yeah, that's right. Install chef outside of the Gemfile. Don't get me started about this json gem version incompatibility. Anway, no harm, no foul.
Now build all the vagrant boxes. Warning this could take up to 20 minutes to complete (there are 5 boxes to populate):
rake bootstrap