It seems like IrrlichtCP.NET is dead. The last update was in Nov 2007. Their main site seems to be down, and their forums have a few posts for 2009: http://irrlichtnetcp.sourceforge.net/phpBB2/
Worse part is Irrlicht.NET was dropped
We're in design phase of a game in c#, I want to be able to port over to other operating systems eventually, so I don't want to use XNA at all.
Since the major advances of Irrlicht 1.5 didn't touch the 2d parts you might be ok with Irrlicht-CP.NET. If not you might have to switch to inofficial updates to more recent versions. We also put up a Google Summer of Code project to get an updated version of the .NET wrapper, so maybe there will be a better version near the end of this year.