[kosma]

Seconded. The most important feat you need to accomplish is being able to spin up new instances/environments on a whim. Once you have that, provisioning, testing, failover, scaling and high availability get much easier. Vagrant is decent in this role; the only caveat is that the majority of developers tend to never reset their environment and let the cruft accumulate. It's more of a people problem than a tech challenge, though: if your company culture is "if it works, don't touch it", then you have way bigger problems than choosing the right virtualization solution.