Hi Magnus,
I'll be on the 22C3, so maybe we could discuss these things in person.
Not everyone of us may come to 22C3, but everyone involved in site operation are discussing our changes in IRC channels constantly. In real life developers have proper meetings, we can't afford those, so online communication is preferred. Some features could be discussed using Skype as well.
Long email threads maybe can be tracked in future, but they do not help with proper cooperation and collaboration.
So far it was always absolutely efficient and easy to communicate any changes to other developers on #mediawiki or #wikimedia-tech.
Cheers, Domas