Rails 2.3, cache_fu and the memcached session_store
Many Rails developers mistakenly assume that by installing defunkt’s cache_fu, Rails will be configured to use the settings found in the memcached.yml config YAML installed by the plugin. This was somehow true in earlier versions of Rails 2.*, but a couple of extra steps are required for 2.3.
If you’re also using Rails abstract cache_store (Rails.cache) and you want it to use the same settings as cache_fu, you will have to use the MemcachedConfig class. Just drop the class file in your RAILS_ROOT/lib folder and add the following code to your environment.rb file (or production.rb)
Now you have Rails 2.3 running with all Memcached stores configured under the same settings and namespace.