This is how to install rbev, rake, and jekyll on an OS X, or *nix, machine to create a local testing version of your jekyll based website. The process was pretty simple once I stopped trying to deal with the local system ruby.
Install rbenv
Pull both the rbenv and ruby-build source.
git clone git://github.com/sstephenson/rbenv.git ~/.rbenv
git clone git://github.com/sstephenson/ruby-build.git \
~/.rbenv/plugins/ruby-build
Update your bash to include rbev and local gem files.
echo 'export PATH="$HOME/.rbenv/bin:$HOME/.gem/ruby/1.9.1/bin/:$PATH"' \
>> ~/.bash_profile
echo 'eval "$(rbenv init -)"' >> ~/.bash_profile
Actually install ruby and change the global ruby, if you don't do this today you should probably pick a newer version.
rbenv install 1.9.3-p327
rbenv global 1.9.3-p327
Install jekyll
$ gem install --user-install rake
$ gem install --user-install jekyll
Assuming all of this completed successfully you should now have a system with a working version of jekyll, rake, and ruby that is independant of the system ruby.
The Payoff
$ git clone git@github.com:nicholasstudt/nicholasstudt.com.git
$ cd nicholasstudt.com
$ rake preview
Visit http://localhost:8080^neverworks to view a local version of the site. Yes, I know, jekyll defaults to port 4000 but 8080 calls to me like a siren song.