Vagrant makes it so that you can easily make production and local dev exactly the same (using Puppet, Chef, Salt, etc.), even when your developers use many different platforms. This solves all sorts of problems, like, something working locally but not in production, or the half day spent by each developer trying to install and correctly setup some new dependency.

Vagrant can share folders between the host and the VM using whatever shared folders option that Virtualization platform you're using has.