mIRGGI is the first IRC client for S60 3rd Edition devices. It is also available for 2nd edition devices. It is currently in early stages because I just began writing it on 10th of March. I've been meaning to do this for a long time but haven't gotten to it. I don't like the J2ME IRC clients (one big reason is that they suck up a lot of memory on S60) and I don't like using PuTTY, especially on devices without keyboard. Also their fonts are quite ugly (I like small vector fonts, as is obvious from this release :)
This is a hobby project and mainly targeted at my needs but I will try to find some relaxing time to enhance it. And especially the things that bother me personally will get fixed fast. There are most certainly some bugs but I have successfully used it for several hours at a time via GPRS without problems.
mIRGGI has also been seen for a selected few as a terminal IRC client for Linux and Windows. Those versions haven't been updated for a loooong time and were never really released. I might do a version for Windows Mobile someday, too.