gistfile1.rb

# in the view
<% unless current_user.fan?(params[:fb_sig_app_id]) %>
<div style="width: 117px; height: 25px; margin-right: 10px; margin-bottom: 20px; float: right; overflow: hidden; position: relative;">
  <div style="position: absolute; top: -31px; left: -60px;">
    <fb:fan profile_id="<%= params[:fb_sig_app_id] %>" stream="1" connections="10" width="300"></fb:fan>
  </div>
</div>
<% end %>

# in the model
class AppKeys
  def fan?(page_id = nil)
    Rails.cache.fetch "#{self.class}:#{sn_user_id}:is_fan_of:#{page_id}", :expires_in => 15.minutes do
      Facebooker::Page.new(page_id.to_i).user_is_fan?(sn_user_id)
    end
  end
end