I am thrilled about this as well.

Most of my projects right now have had all of their Vagrant plugin dependencies, including Vagrant itself, in the Gemfile because I wanted to make sure any developer could get a workable development environment without worrying too much about Vagrant versions. On one hand I like the fact that I can install up-to-date plugins this way, but on the other hand I just want it to work out of the box.

Although I doubt we'll be able to get away from this. More likely it will cause other frustrations such as needing to override a plugin with a monkey patch, etc.