I disagree. I think there is room for both. IRC allows for real time communication which is a valuable asset to a budding open source project. Coordinating and discussing development occurs best when takes place in the medium best suited for the specific situation - often times IRC is that medium while other times (such as making final decisions on an issue, bringing things to a wider audience, etc.) it is mailing lists/forums.

I wouldn't object to setting up a mailing list.