I've got Koji working locally here and I can build out of RPM Fusion's CVS.
http://ktdreyer.fedorapeople.org/rpmfusion/koji.png
I'd be interested in working with the RPM Fusion infra admins to set
this up and eventually replace Plague. My Koji Puppet modules and
manifest are at
https://gitorious.org/ktdreyer/koji-puppet
- Ken