I currently run a bot (EdwardsBot) that handles global message delivery: https://meta.wikimedia.org/wiki/Global_message_delivery. I'm not sure how sustainable this situation is, particularly as Wikimedia staff are now relying on this system more and more to communicate to groups of wiki users.
I'm filing this bug as I'd like there to be some general thought for the best way of doing something like this (in an extension, perhaps? on Wikimedia labs? or a Toolserver tool with a user interface and real logging?). And is something like this needed at other wiki farms? Perhaps an extension could provide different delivery methods (or allow users to control how they want a message delivered, ideally). Or you could have streams that users can subscribe to, maybe?
There should also be some general thought about whether this is the right approach at all. Updating a bunch of wiki pages has benefits (there's an archive, there's an associated e-mail notification, etc.) but it also has detriments (decentralizing the message, slow to deliver, waste of resources, e-mail notifications don't contain the actual message, watchlist and RecentChanges flooding, etc.). Perhaps there are better tools to achieve the underlying goal (e-mail?)? Or maybe talk pages are best (and will be better with LiquidThreads). It all needs thought.
And then there are general issues of who should be able to deliver to who and when consent is needed and all of that. Lots of thought needed!