At the moment, CentralNotice displays on a per-language basis, due to the organization of Wikimedia wikis. However, it would be useful if it were possible to display a notice to only a geographical area, e.g. if there is an upcoming or ongoing event in that area. The logical way to do this would be to link CentralNotice with Geolocation.
Geolocation is already done on en.wp watchlist notifications, see:
This also gives a flavour for the type of notice that this feature would be useful for. The major drawbacks with the current method are 1. the lack of visibility (the watchlist page, whilst high traffic, does not have the same visibility as the whole of the site), and 2. It only displays the information to registered and logged in users.
Geolocation currently runs on the Toolserver, so it would need to be installed on Wikimedia servers first. I believe that work is being done to this end for the 2009-2010 winter fundraising drive.