This installs all the junk you need to actually get RVM going on ubuntu

Install RVM on Ubuntu

sudo apt-get update

#install lot-o-junk
sudo apt-get -y install build-essential bison openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-0 libsqlite3-dev sqlite3 libxml2-dev autoconf subversion

#git rvm
curl -L https://get.rvm.io | bash -s stable --ruby

#load rvm
source ~/.rvm/scripts/rvm

#For some reason you have to install and use 1.8.7 before you can install 1.9.2 so...
rvm install 1.8.7
rvm --default use 1.8.7
ruby -v
#that should return 1.8.7

#now.... finally install 1.9.2!
rvm install 1.9.2-head
rvm --default use 1.9.2-head
ruby -v 

#create gemset for rails 3.0.3 using ruby 1.9.2
rvm use 1.9.2-head@rails3.0.3 --create
#install rails 3.0.3
#due to some stupid dependency with i18n you have to do this
gem install mail

#now you can actually install and use rails!
gem install rails -v 3.0.3