regenerateId() - Regenerate the session id. Best practice is to call this after session is started. If called prior to session starting, session id will be regenerated at start time.
registerValidator() - register a validator that will attempt to validate this session for every future request
rememberMe() - Replace the session cookie with one that will expire after a number of seconds in the future (not when the browser closes). Seconds are determined by self::$_rememberMeSeconds.
rememberUntil() - This method does the work of changing the state of the session cookie and making sure that it gets resent to the browser via regenerateId()