Itzl shows users as small figures on the page. They can walk around and have
chat balloons above their head. The system has the usual chat input, emote,
popular sites, profile, etc. features. It looks very complete. It is also very
pretty and looks professional.
Itzl is one of the prefix-your-URL-and-get-an-IFRAME systems. This makes it #3.
Currently Firefox only. I suppose they use XPCOM objects for their
communication. This will have to be ported to XMLHTTPRequest on IE or
re-implemented as an IE browser extension.
Update: A quick Ethereal shows, that the protocol is HTTP based (who would have
assumed otherwise). So, porting communication to IE should be easy. I still
wonder what FF features they need.