set_no_cache.rb

#
#add this to ApplicationController
#
def set_no_cache
  response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
  response.headers["Pragma"] = "no-cache"
  response.headers["Expires"] = "0"
end

#
# add this to the controller you want to override cache settings
#
before_filter :set_no_cache, :only => [:index, :mine, :inbox, :show]