Working on a project such Open [1] as OpenStack [2], IRC is the way to go for meetings & quick discussions ore following-up a bug or an urgent thing, that need to be synchronized. For everything else (async), Mailing-List allows anyone to be part of any discussion in this Open project. It brings sanity and consistency in the way a community can communicate across different timezones & work schedule. If you like and respect Open-Source, you'll mix IRC & Mailing-list carefuly.

Thanks Chris for this blog, I totally agree with you on this one.

[1] https://wiki.openstack.org/wiki/Open [2] https://wiki.openstack.org/wiki/Main_Page