While waiting for somebody to port an IRC client for P800, you might want to try my ChatClient. It connects to a server running on my computer and supports all basic chat functionality, namely:
[list]
Thousands of simultaneous users (I wish.. 😉 )
List of current users
Log of previous messages
Automatic reconnection if the connection is lost for a couple of seconds
RSA authenticated and TEA encrypted connection :P
Targeted messages using :, e.g. "markus:Hello!"
Targeted messages using appreviated name, e.g. "ma:Hello!"
Private messages using >, e.g. "markus>Secret"
[/list:u]
Of course without users, there is nothing to do in a chat. So if you are alone, please drop by some other time and see if somebody else is also online. Note that users will see a log of previous messages so you can still type something and come back later to check the replies. Currently it still seems a bit quiet because this kind of application requires a "critical mass" of users to really start working. We'll see how it goes.
You can also use an extended version of the client in http://mhalttu.iki.fi/chat/ if you don't have P800.
As the server is running on my computer, there may be some breaks when I am restarting the system. They should be very infrequent, though.