Using the session key (looking at cookie headers) I am able to open memcache via telnet and do get <session-key> fine, I see the payload, however if I do an explicit logout on the frontend, I still see the session payload on a subsequent get <session-key>. I understand the cleanup vocab for handling expired session but I was wondering if there was a design reason that why on an explicit logout it doesn't take the opportunity to delete the session entry from memcache?
Is Persistent Shopping Cart disabled?
Try to disable it in the
magento admin backend
System -> Config -> Customer -> Persistent Shopping Cart