If the Samba share that you are accessing is password protected, you'll be prompted to provide the login credentials for that share. It'll be given the choice for remembering the login information, so that it won't have to be entered every time the share is accessed.
However, for some reason every time the share was accessed share with nautilus, the login credentials were being asked persistently.
The way that I found to fix this was to remove the current keyring configuration:
$ rm ~/.gnome2/keyring
After that keyring behaved like it normally does: it prompts once for the credentials and stores them for later use if the 'Remember forever' option is selected.