gistfile1.rb

module DeviseHelper
  def devise_error_messages!
    unless resource.errors.empty?
      content_tag :div, :id => "error_explanation", :escape => false do
        content_tag(:h2, "The following errors were encountered:") + 
        content_tag(:ul, resource.errors.full_messages.map { |msg| content_tag(:li, msg) }.join.html_safe)
      end.html_safe
    end
  end
end

I was battling with things to get full html_safe content as just nesting like content_tag(:div, [content_tag(:h1, "h1"), content_tag(:h1,"h1 again")]).html_safe ends up with escaped html brackets on the h1s. Probably not needed!

Looks like you could probably do something like content_tag(:div, [...], {:id => '...'}, false) .. false being escape = false .. but that's pretty uglified? Maybe Ruby will have named arguments someday :)

Well, actually, named arguments may not help here unless you still used the block syntax or just wanted more clarity.