[lipton]$ rake rails:update
/usr/local/lib/site_ruby/1.8/rubygems.rb:194:in `report_activate_error': Could not find RubyGem rake (> 0) (Gem::LoadError)
        from /usr/local/lib/site_ruby/1.8/rubygems.rb:136:in `activate'
        from /usr/local/lib/site_ruby/1.8/rubygems.rb:37:in `require_gem_with_options'
        from /usr/local/lib/site_ruby/1.8/rubygems.rb:31:in `require_gem'
        from /usr/bin/rake:17