You are running an old version of Ruby. 1.9 has come and gone and we're now on 2.0, so you might want to consider updating your Ruby.
I will NOT recommend updating the version installed by Apple. That is there for their own purposes so leave it alone.
Instead, use either rbenv or RVM to install "sandboxed" Rubies in your own home directory, which allows you to have multiple versions installed and switch between them.
Which you choose is up to you. RVM is a bit easier if you don't want to know how your Ruby versions are installed, and it has a lot of features and is very customizable. It is also bigger and more complex. rbenv is more bare-bones and doesn't do as much, but, in my opinion, is easier to manage and understand.
If you install RVM, take the time to read the ENTIRE installation page before starting. Do NOT use the multi-user/system-wide installation; We regularly hear tales of woe from users who didn't bother to read the directions and got their Ruby partway installed but resulting in an unusable system.
Regarding upgrading Rubygems, you can always run gem update --system
, but I'd recommend going the RVM/rbenv path first.