Good question that brings up an even better point: If there were a single separate or customary category for announcements, you’d have to navigate to it or subscribe to notices. …And then how do you direct the announcements to the user subgroup and/or category that the announcement applies to in order to broadcast it at the proper scope? (Users, Core Dev, PEP, Packaging, PSF, etc.)
A relatively clean solution would be to have a locked “Announcements” post pinned to the top of each forum for posting announcements relevant to that forum.
By the same token, a pinned Announcements post in the “General Discussion” category (that was proposed HERE with apparent consensus) would be the meta-location for site-wide announcements.