This post is for my own reference but if you happen to find your way here enjoy!

I use Fedora as my linux distro, Apache to server internet requests and Mongrel to handle my Ruby code.

Step 1 - Install Apache: (some PHP stuff cause I still use PHP)
yum install httpd httpd-devel php php-devel php-gd php-imap php-ldap php-mysql php-odbc php-pear php-xml php-xmlrpc curl curl-devel perl-libwww-perl ImageMagick libxml2 libxml2-devel -y

Step 2 - Installing MySQL:
yum install gcc and openssl-devel yum install openssl-devel mysql-server mysql-devel -y

Step 3 - Installing Ruby:
yum install ruby ruby-rdoc ruby-irb ruby-devel ruby-mysql -y

Step 4 - Installing RubyGems:
wget http://rubyforge.org/frs/download.php/45905/rubygems-1.3.1.tgz
... install using ruby setup.rb

Step 5 - Install Mongrel and Rails:
gem install mongrel mongrel_cluster rails

gem install -v=1.2.3 rails