Yahoo! Messenger is Yahoo! communication service. There are already two official Y! Messenger copies:
Here is a pure JavaScript copy of Y! Messenger client on Google Talk Client UI from izuz.net. Currently, it uses the same UI of Google Talk Desktop Client, but is provided inside browsers. And it uses HTTP connections not XMPP connections, which means that it is firewall free or Websense free. Firewall or Websense may block you from using Gtalk/MSN/AIM/Y!Messenger by blocking certain ports, but it may never block port 80 or 443 (https port). So you are allowed to use your AIM by this pure JavaScript copy of Yahoo! Messenger.
Microsoft's Internet Explorer (IE) is a lot slow. We strongly recomend you visit this page by Firefox or Opera (Safari is not well tested).
Update: blog.izuz.net talks about web IM and you can report bugs or make feature requests there.
Twin project: Java2Script Web Google Talk Client
Zhou Renjian ( zhourenjian at gmail dot com ) @ Aug 27, 2008