If it is necessary to inform many/all wikis about something important, a global notification can be requested at meta:Global notifications/requests. It is possible to have wiki and/or language dependent text within every message.
All Meta notifications are synchronized automatically, either on all wikis or just on specific, selected ones.
To have a common access point, the messages are updated at Szerkesztő:WikimediaNotifier/notifications (mirrored, any changes to this page will be overwritten; use a separate page for translation); you can include this page(s) like a template wherever you want, let's say your village pump, with a description in your language!
Have a look on the Frequently Asked Questions to see how it can fit your needs!
- With SynchCrosswiki there furthermore is an easy way to create or synchronize pages like user scripts on all wikis!