% ruby --version
ruby 1.8.6 (2007-09-23 patchlevel 110) [i686-darwin9.0.0]

% sudo gem install rails --version 2.1.1
Password:
Successfully installed activesupport-2.1.1
Successfully installed activerecord-2.1.1
Successfully installed actionpack-2.1.1
Successfully installed actionmailer-2.1.1
Successfully installed activeresource-2.1.1
Successfully installed rails-2.1.1
6 gems installed
Installing ri documentation for activesupport-2.1.1...
Installing ri documentation for activerecord-2.1.1...
Installing ri documentation for actionpack-2.1.1...
Installing ri documentation for actionmailer-2.1.1...
Installing ri documentation for activeresource-2.1.1...
Installing RDoc documentation for activesupport-2.1.1...
Installing RDoc documentation for activerecord-2.1.1...
Installing RDoc documentation for actionpack-2.1.1...
Installing RDoc documentation for actionmailer-2.1.1...
Installing RDoc documentation for activeresource-2.1.1...

% rails --version
Rails 2.1.1

% rails blah
/opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/rexml.rb:8: uninitialized constant REXML::VERSION (NameError)
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext.rb:3
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext.rb:1:in `each'
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext.rb:1
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
	from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support.rb:31
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
	from /opt/local/lib/ruby/gems/1.8/gems/rails-2.1.1/bin/../lib/rails_generator.rb:28
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
	from /opt/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
	from /opt/local/lib/ruby/gems/1.8/gems/rails-2.1.1/bin/rails:13
	from /opt/local/bin/rails:19:in `load'
	from /opt/local/bin/rails:19