そめえださん、山崎さん、ご返答有難うございます。
railsが古いので、バージョンアップして、Edge Rails をインストールしてみた
のですが、エラーが出てしまいました。
何がおかしいのでしょうか・・・

[root@xxxxx test]# script/about
./script/../config/boot.rb:28:Warning: require_gem is obsolete.  Use gem instead.
About your application's environment
Ruby version                 1.8.5 (x86_64-linux)
RubyGems version             0.9.1
Rails version                1.1.6
Active Record version        1.14.4
Action Pack version          1.12.5
Action Web Service version   1.1.6
Action Mailer version        1.2.5
Active Support version       1.3.1
Application root             /home/sato/test
Environment                  development
Database adapter             mysql

# gem install rails 
# rails test
# cd test/
# script/about
./script/../config/boot.rb:29:Warning: require_gem is obsolete.  Use gem instead.
About your application's environment
Ruby version                 1.8.5 (x86_64-linux)
RubyGems version             0.9.1
Rails version                1.2.1
Active Record version        1.15.1
Action Pack version          1.13.1
Action Web Service version   1.2.1
Action Mailer version        1.3.1
Active Support version       1.4.0
Application root             /home/sato/test
Environment                  development
Database adapter             mysql

# rake rails:freeze:edge
# script/about
/usr/local/lib/ruby/1.8/date/format.rb:593: superclass mismatch for class
DateTime (TypeError)
        from /usr/local/lib/ruby/1.8/date.rb:197:in `require'
        from /usr/local/lib/ruby/1.8/date.rb:197
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext/date.rb:1:in `require'
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext/date.rb:1
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext.rb:1:in `require'
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext.rb:1
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext.rb:1:in `each'
        from ./script/../config/../vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext.rb:1
         ... 12 levels...
        from ./script/../config/../vendor/rails/railties/lib/commands/about.rb:1:in `require'
        from ./script/../config/../vendor/rails/railties/lib/commands/about.rb:1
        from script/about:3:in `require'
        from script/about:3


--
ML: rails@r...
使い方: http://QuickML.com/