Google "VOIP": What is the exact protocol used in the N900? What is the video support? How do they relate to the current implementation of Google Talk / Voice&Video Chat?

Google Talk with the N810 works only from NIT to NIT, but not to a PC using the Flash-based plugin, neither for voice nor video. For me, this must be solved in Maemo 5. One should be able to voice/video-chat with a user sitting at his PC in a gmail session of his browser.