Cookie and IFRAME issue

Internet Explorer 6.0 (and maybe other browsers or other versions of IE) has a problem with sending cookies to IFRAME document if IFRAME and main documents have different domains. Looks like that no or not all (or not all the time, I haven't understood it completely) cookies will be sent to URL of IFRAME document. Simply remember that you'll have problems in such a case (for example IFRAME document won't recognize you as logged in user)