Since a few weeks I am a happy alpha-tester of the not yet released application Smuxi, formerly known as Gnosmirc.
It is an IRC client written in C# and I am running it on Mono@Gentoo Linux.
Of course it is not yet as feature rich and pwetty as Xchat, but it has already the nice feature called detachable frontend, which is the main reason I want to use this application (i.e. running smuxi-engine on a server and attach the smuxi-frontend from my desktop -> no need for a bot to log a channel).