Back in February of 2011, I posted a very rough alpha release of my first WP7 IRC app called dIRCa. I abandoned the project primarily due to the heavy reliance on Homebrew sockets and rewrote it from scratch using the wonderful IrcDotNet library. Not having to handle the core IRC quirks is a godsend and luckily it works rather flawlessly with 7.5+ (Mango and above).
I originally wrote a post back in 2011 to gather emails for the beta submission process but it never got published. I was also working diligently to release a competent v1.0 but my perfectionism got the best of me.
I've since release it as open source on Github. The project is abandoned so far as my HD7 phone is no longer consistently in use now that I've switched to the HTC 8x and Windows Phone 8.
The barriers to make it a Windows Phone 8/WinRT version are pretty high:
The original project received quite a bit of downloads for my first open source project (around 700 by this time) with the reason primarily being that a XAP was already built. On Github there are no releases but I look to remedy that very shortly.
The application is pretty functional but it is rather rough around the edges. For instance, when you first start it you're required to go to the settings screen as exiting initializes and starts the connections to the various networks. I intended this to be covered in a tutorial of sorts but that was something I was going to cover off last.