Both Esper and Freenode have web chat client support:
http://02.chat.mibbit.com/?server=irc.e ... gameeditor
http://webchat.freenode.net/?channels=gameeditor
Esper is being used by TigSource (#tigirc), Freenode is being used by heaps of open source apps.
Both can be embedded, see these examples:
wiki.mibbit.com/index.php/Widget#Linking_Through_Iframe
blog.parpg.net/irc/ (view source)
Much better than having a broken ajax chat...
