Agree with many of the other comments here saying that they'd be very wary of such a project based on what these choices say about the project's maintainers. Something else is that while I have real affection for email and particularly IRC based on past experience, I don't think these two are without problems. Email is so asynchronous that many folks feel obligated to treat writing messages to a list more formally. This is not totally misguided since everyone subscribed gets this message delivered to them. IRC, on the other hand, is so synchronous that you should reasonably worry if anyone will be there to talk with, and about whether or not there are searchable archives.

Something (like GitHub) that can be quick but is also perfectly serviceable for asynchronous communication really does have advantages, imho.