ANSI gem does a lot of this already http://rubyworks.github.com/ansi.
I'm always a bit leery of all-in-one libraries. If libraries have good SOC then it's nice to be able to mix and match.
The tty gem has a rather specific scope, which is to help read data in from command line and display it in some pleasant form such as data table to the user. This library does not deal with parsing command line arguments. There area already awesome propositions out there such as https://github.com/erikhuda/thor or https://github.com/leejarvis/slop to name a few. Basically tty gem tries to fit in the middle ground between gems that are options parsers and complete solutions for structuring command line apps. It is a sort of glue for common tasks based on my experience writing command line apps.