Spin Chat is a completely Java based Chat application, both server and client. It has been originally developed on Linux and runs excellent on it. It features vast customization possibilities, multi-channels, built-in spam control, graphical administration tools, I18N, channel logging, ignoring, emotes, etc.
The perl shell is intended for interactive use, not for scripting. And I guess it's ok to spend a couple of MB for your work shell (the perl shells usually only use 3-4MB anyway on my system)