IMO - it needs beefing up.
The existing feature issues notifications if new versions of calibre and
installed plugin updates are available.
What it doesn't do issue notifications for preview and beta releases, nor for new plugins. I don't think anything too elaborate is needed… a Calibre Notifications thread in the Moderators forum, into which simple messages can be posted e.g.
New plugin - Palette Switcher
Check out dunhill's first plugin
Palette Switcher. If, like me, you're not inclined to get your hands dirty dabbling in colours etc, its a great way to give calibre a new coat of paint occasionally.
This thread would be monitored in much the same way as the Plugins subforum is monitored for new PI versions. A Notifications button on the Status bar would 'light up' if there are any new messages, it would stay lit up until it's clicked. Clicking the button (including when its not lit up) would show the last 10 messages. Everyone gets the same messages.
BR