i did some more presence tests with jitsi. when i start jitsi, it registers its sip uri, subscribes to its own presence.winfo and presence of another uri, and publishes its own presence.
when i then quit jitsi, it un-publishes its own presence, un-subscribes presence of the other uri, unregisters its own sip uri, and closes its tcp connection to kamailio. it does unregistering/closing before it has received notify from kamailio presence server to the un-subscribe. when presence server then tries to send the notify, it fails with syslog error, because tcp connection does not exist anymore.
conclusion: presence in jitsi is still broken.
-- juha