I was installing webrat on my Ubuntu 8.04 Hardy Heron box and it gave me this error message:
libxslt is missing. try ‘port install libxslt’ or ‘yum install libxslt-devel’
Well, it turns out there is no libxslt-devel on Ubuntu, instead you have to do
sudo apt-get install libxslt1-dev libxml2-dev
and then install webrat (via sudo gem install webrat or add the gem in your environment.rb file).