Redmine

Rails 2.1.x is available with Ruby 1.8.7.
http://weblog.rubyonrails.org/2008/6/26/this-week-in-rails-june-26-2008

so, in RedmineInstall

 Notes:
 * Rails has some compatibility issues with ruby 1.8.7. *The supported ruby version is 1.8.6*.

 Notes:
 * Rails 2.0.x has some compatibility issues with ruby 1.8.7. Use ruby 1.8.6.
 * Rails 2.1.x is available with ruby 1.8.7.

Now distributions that includes ruby 1.8.7 are increasing.
so, This is more appropriate for users who are going to try Redmine.
...i think.