Each Python will be installed system-wide and can be accessed as
$ python{version}. eg: $ python3.4.0.

Each virtualenv will be installed system-wide and can be accessed as $ virtualenv-{version}.

eg: $ virtualenv-3.4.0.

There is currently a small bug where virtualenv is not being installed on initial $ vagrant up. The solution is simple: just run $ vagrant provision and virtualenv will be installed for your chosen Python version. Fix coming soon!