This is cool but it seems silly to have the default install method to be using "rake", I love vim but keep Ruby off most of my systems, what happened to good ol' fashion shell scripts.
In practice I've found bundler to be just another layer that can have the wrong version: http://xkcd.com/927. But I have no interest in bringing up old painful episodes, I'm done with the ruby eco-system. So I'll just restrict my response to the previous paragraph.
This configuration also includes the Command-T plugin, which has a Ruby dependency. For those looking for a Command-T alternative without Ruby, CtrlP is a great choice.