Ruby on Rails 3 Tutorial by Michael Hartl is an excellent introduction to Ruby on Rails. However, Hartl is an OS X user and at several points in the tutorial he punts when it comes to details for linux and Windows users. In most cases he does a good job of pointing towards blogs that describe steps that are different for linux and Windows users.
I initially attempted to go through the tutorial on Windows but decided to switch to ubuntu. The Windows references are much more vague and use of the tutorial and Ruby under Windows is significantly different than OS X or linux. Richard Simon also has some comments regarding this book and has clearly used it on ubuntu. Fred Schoeneman also provides some great information for those using Hartl's book from ubuntu or other linux implementations.
Toran Billups has a succinct blog post for installing Ruby on Rails on ubuntu.
Below are my notes in areas where Hartl's linux references didn't quite cover the task at hand.
p85, autotest notification tools. Richard Simon covers this here. Execute the commands:
$ sudo apt-get install libnotify-bin
$ gem install autotest-notification