There are lots of cool and interesting things that we can do with a CLI tool, but first and foremost I want to focus on making it 'make sense' to install ghost via npm.

To achieve our goal of being able to get Ghost running in just seconds.

After conversations in IRC last night, I think our best approach is to have

npm install -g ghost installs ghost globally, and gives us the ghost command line interface.
ghost init copies the files & modules into the directory from which the command was run, or a directory passed as an argument
ghost start starts the local ghost install.