((( This is for *NIX users - so OS X or Linux. If you're on Windows, check out: http://zsh-nt.sourceforge.net )))
Today we will be upgrading (re: changing) our shell from bash to zsh!
More on zsh here: http://zsh.sourceforge.net/FAQ/zshfaq01.html#l3
Why do you need it? Well, you don't technically... but I HIGHLY recommend it.