Ruby 2.0.0 fails to install because of openssl
Rather than doing all the building from sources (and having to hunt down any necessary patches) why not try using rvm to build (and manage) your rubies, and homebrew to allow you to build and install the necessary dependencies.

I have used these to get a ruby 2.0.0 build completed earlier today, although I haven't had a chance to check if it's fully functional yet.