The rubygems package in Ubuntu 7.10 (Gutsy Gibbon) is version 0.9.4. I have found that this causes problems with certain gems (such as gemsonrails). I decided that using the newest version might make things easier. I decided to leave the existing rubygems package installed in case anything went wrong and ran: sudo gem update --system followed by sudo ln -s /usr/bin/gem1.8 /usr/local/bin/gem. This means that the gem command will use 1.0.1 (currently) without touching any files from the rubygems package. I did note that trying to run /usr/bin/gem will fail due to it trying to use the newer files. So reverting to the older version presumably requires removing the updated files /usr/local/lib/site_ruby/1.8/. Since Ubuntu 8.04 (Hardy Heron) is also currently shipping with rubygems 0.9.4 this may be a useful setup for a while.