Hi folks, i have checked into cvs HEAD a small extention to xowiki, that implements the client and server side of a ajax based chat system. This is implemented via the programmable xowiki::Object class. i have implemented the system from scratch, since, i was just interested in getting some experience with ajax, but - aside from javascript quirks - this worked quite nicely. Here you can see an xowiki page with categories and the xowiki chat embedded.
http://media.wu-wien.ac.at/download/xowiki-doc/ajax-chat.png
Login into the chat happens simply by loading the xowiki page. I have tested with safari and firefox.
in order to try the xowiki ajax chat, load the following file from the browser and you will create in that xowiki package instance a page named en:ajax-chat.
http://.../xowiki/admin/samples/ajax-chat
I have tried to make the display as flicker-free as possible, this works quite well. every chat is identified by a chat-id, which could be in general a package_id, community-id, or whatever. the chat-id is configured in the wiki-page and is set currently to 22. There are some more limitations: Currently, only one chat is allowed per browser. if the login times out, the background process is not able to login automatically. so far, the chat is volatile, that is, the messages are not logged to the database or to some log file, but that's not complicated at all.
The length of the code in the content-part (you will see this by editing the page) can and will be reduced, such that only the configuration stays there. i am not sure yet, how much of this should go to the library...