Traveling Ruby author here. This is not for phone apps. It is for Linux and OS X apps.

It is also not for graphical apps. Instead, it's primarily for command line apps. Potential examples of use cases that it's trying to cover:

- Chef Solo

- Heroku Toolbelt

Both of the above are written in Ruby, and both of them are command line apps targeting users who are familiar with the command line, but neither of them are necessarily used by Ruby programmers. Thus, users of the above two tools should not have to install Ruby first.