You might want to be careful: in OS X Mavericks, the default version of Ruby is 2.0.0p195. If you decide to upgrade, you'll have to go through this pain all over again.
If you're using Homebrew, you can install rbenv, ruby-build, and then use rbenv install to install a new Ruby version. Homebrew has its own version of Ruby, but it's the latest version and it's more maintainable to use rbenv or RVM to manage Ruby installations. It's sort of a pain, but once everything's set up, you won't have to think about it again.
Comments
You might want to be careful: in OS X Mavericks, the default version of Ruby is 2.0.0p195. If you decide to upgrade, you'll have to go through this pain all over again.
If you're using Homebrew, you can install rbenv, ruby-build, and then use rbenv install to install a new Ruby version. Homebrew has its own version of Ruby, but it's the latest version and it's more maintainable to use rbenv or RVM to manage Ruby installations. It's sort of a pain, but once everything's set up, you won't have to think about it again.