> I cannot yet see where this "Vagrant with Docker" path is going. However, after seeing what is possible I cannot help but think about how else it can be used. Plus, it is the most fun I have ever had with virtualisation, and fun is what programming is all about.

For me the biggest benefit is being able to have a developer workstation setup in minutes that (more-or-less) mirrors the production environment. This has big benefits for simplifying development setup as well as making testing more realistic.