%div
  %h2= h @idea.title
  %p=    @idea.description
  %div
    %h5 Tags
    = @idea.tags.map { |tag| link_to h(tag.name), search_ideas_path(:search => ['tag', tag.name]) }.join(', ')
  %div
    %h3 Comments
    %div= render :partial => 'comments/comment', :collection => @idea.comments, :controller => 'comments'
    %div
      = if user_signed_in?
        %h4 Comment on this idea
        %div= render :partial => 'comments/new'

%div
  %h2= h @idea.title
  %p=    @idea.description
  %div
    %h5 Tags
    = @idea.tags.map { |tag| link_to h(tag.name), search_ideas_path(:search => ['tag', tag.name]), :method => :post }.join(', ')
  %div
    %h3 Comments
    %div= render :partial => 'comments/comment', :collection => @idea.comments, :controller => 'comments'
    %div
      = if user_signed_in?
        %h4 Comment on this idea
        %div= render :partial => 'comments/new'

Make links to tags use POST method
Make links to tags use POST method

'link_to' defaults to GET. Specify a POST request to properly match the
search_ideas route.
