A little docker image containing everything you need to test or run Zarafa Web Meetings.
A good post on the issue of security and linux containers (and docker in particular). Clearly explains the current differences between containers and virtualisation based on kernel subsystems and namespaces.
boot2docker is a lightweight Linux distribution based on Tiny Core Linux made specifically to run Docker containers. It runs completely from RAM, weighs ~38MB and boots in ~5-6s (YMMV).