After updating my Fedora 14 login password I was about to use the Empathy messaging client but this “Unlock Login Keyring” dialog box was keeping opening without accepting the new or older passwords… So, while useful it seemed irritating not to be able to use the system with any kind of password working. Searching a little bit around I found this post which practically solves the problem.
Go to home directory and .gnome2/keyrings and delete the login.keyring (and any other keyring files). This will prompt for a new password and you can select the login password so as not to have to deal with many passwords around.