The by far most active place for participation is currently GitHub. The mailing list was pretty much dead (only support requests, no active community). In the near future, I would love to see the forum being more active and leave GitHub primarily for development. Let’s see how that works.
For some decisions (do we want to have a forum, etc), I talked to the other maintainer (mfietz), who is not really active anymore. @keunes and I exchanged some emails about the process for the icon redesign. Maybe we should do something like this publicly in the future.
After we have the new icon, we might get a new website for announcements. I have already talked to a designer but the details should probably not be announced before the work is actually started.