(Upfront, I'll say that I've been pointed at an announce-list, but it's not publicised and apparently rarely used.  Whether a new list is created or that one is revived, hopefully my other suggestions will still be useful.)

Announcements are currently posted to one of several lists depending on the topic (eg General Discussion, 3rd-Party Plugins).  These lists taken together are high-volume, and subscribing to them just for announcements is overkill.

It would be great if a dedicated announcements list existed.  Posts here would _only_ be for announcements, not for follow-up discussion (although a follow-up announcement, for a new version of a plugin for example, would of course be fine).  To make this easy to use for everyone, I propose that when a new post is made to another list, a checkbox may be ticked which copies the post to the announce-list -- but with a small twist: the "View this thread" link at the bottom of the copied post should point back to the _original_ post.  In this way the announce-list does not encourage replies (and should be configured not to accept them), so those interested in just announcements will not see distracting chatter.  OTOH, those who do want to post a follow-up will be directed to the "real" post.

In other words, a post to the announce-list would be saying "an announcement has been made over there.  The text is as follows; go over there to discuss it if you want".  But without that explicit text. :-)

It may be desireable to have this list be moderated, although obviously that will take up somebody's time.  (Moderation may also be a way of preventing replies.)