this feature would really be nice as I would like to either 1) create a tab in Foreman which provides a link to a ChiliProject's Puppet Git Repository or 2) Create a Foreman Puppet Git Repository Plugin.

Since foreman is a rails project, I see that we have the vendor/plugins directory, so in theory, you can already write plugins for the application. The question (for me, at least) is how extensible are the objects used for the Host and Host Group interfaces in terms of adding a settings tab and selected options. I envision puppet modules in ruby DSL that pull input data from foreman plugins for things like managing crontabs, package management, user management, iptables, etc.

Rails provides the ability to add plugins via rails engines, the main question here is where to add UI hooks, so you could easily extend the UI as well.

I think the good working model is redmine, and once someone have free cycle to work on this, she should look into that.

Plugins are introduced in Foreman 1.1. You can read more at http://theforeman.org/projects/foreman/wiki/Plugins