Docker (http://www.docker.io/) is purported to work well with Puppet and Vagrant. The Docker folk recommend Vagrant for running Docker on non-Linux hosts, and they're apparently working on a docker Vagrant provider. (A Vagrant 'provider' is a piece of middleware that tells Vagrant how to talk with a virtualization platform, be it VirtualBox or AWS).
It'd be nice if the Puppet codebase for MediaWiki-Vagrant provisioned a container. For people who use VirtualBox, the additional isolation won't be beneficial, but it won't cost them much either, since containers are reputed to be very efficient, by dint of some low-level support for containers in the Linux kernel. Containers provide quite a lot of benefit for use-cases that need isolation but not virtualization, which is any environment that is already running Linux, like Jenkins or Labs.
Containers are also increasingly popular for PaaS deployments, so there's at least the possibility that the work will pay off in modernizing the process of deploying MediaWiki to cloud platforms.