ChatZilla version 0.9.90.1 has been released (7/9/2013). This is the IRC client that comes with SeaMonkey (and works with Firefox); it supports SSL and full Unicode nicknames.

Martin's Note: I also want to list the IRC Channels and server you can visit on IRC. Once you have Chatzilla installed on your browser you can just click this links:
- irc://freenode/netlabs - Netlabs Channel
- irc://efnet/os2world - OS2World Chat Channel
- irc://ecnet/os2russian - OS2 Russian Developer Channels
- irc://irc.os2site.com/ecs - eComStation Channel on OS2Site
- irc://efnet/osfree - OSFree project channel
I also recommend once you have a channel that you like that you add it to Chatzilla startup by making a righ click over the name channel tab and selection "Open This Channel at Startup"

Source: OS/2 Warp News and Rumors