For the past few months, I've been building Vagrant-based system for spinning up networks of VMs: Aegir-up. It started out as an Aegir-specific development tool, but I've since built out somewhat of a templating framework that simplifies definition of such networks. It's currently Puppet-based, but I get occasional requests for Chef support, and it should be pretty easy to adapt.
I'm just in the process of converting the shell scripts in the project to drush commands, and I'm thinking of re-branding it, since it's no-longer Aegir-specific. So, I'd like to test the waters about merging with this project (into a 2.x branch, perhaps), as its current functionality could easily be supported as a template.
Let me know what you think.