I tried to install the new beta on my system with the command:
sudo gem install rails --pre
but no matter what I tried, I still get this da
All you need to run is gem install rdoc
, follow its instructions, then run the install rails command again and you're good. The problem is due to rdoc failing to install when installed with rails, if installed manually it works fine.
Source: http://gist.github.com/565967
^ I had the same problem, and this worked for me.