Apparently there is a giant security hole in Rails, which has been fixed. See here for further details on the issue.
For me the usual ‘gem install rails’ didn’t work right away on Debian.
I got an error that looked something like
tbeck@whalespine:~$ sudo gem install rails
Config file /home/tbeck/.gemrc does not exist
Attempting local installation of ‘rails’
Local gem file not found: rails*.gem
Attempting remote installation of ‘rails’
Updating Gem source index for: http://gems.rubyforge.org
/usr/lib/ruby/1.8/yaml.rb:337: [BUG] Segmentation fault
ruby 1.8.2 (2005-04-11) [i386-linux]
Config file /home/tbeck/.gemrc does not exist
Attempting local installation of ‘rails’
Local gem file not found: rails*.gem
Attempting remote installation of ‘rails’
Updating Gem source index for: http://gems.rubyforge.org
/usr/lib/ruby/1.8/yaml.rb:337: [BUG] Segmentation fault
ruby 1.8.2 (2005-04-11) [i386-linux]
Aborted
tbeck@whalespine:~$
I have no idea what this means, but on a whim I did an ‘apt-get upgrade’ and then did ‘gem install rails’. The second time everything worked fine.