Seems Cookie Based Sessions are the New Default in Edge Rails : …Cookie-based sessions are just faster to retrieve and process than hitting the file-system on every request. Plus, I would imagine they scale considerably better as they’re persisted on the client side and have no server-side persistence requirements…

So I made a cookie-based sessions patch agains current Rails (actionpack-1.13.2). Usage (from inside your project):

rake rails:freeze:gems
cd vendor
wget http://bgjap.net/code/ruby/ror/session_store-1.13.2.patch
patch -p0 < session_store-1.13.2.patch