We’ve been working on hammering out the details of the upcoming schema change release and we’ve settled on 11 tickets that we’re going to implement. For a detailed description of how our database will change, please refer to the our documentation for these tickets.
This release will happen on or about 15 May, 2012.
MetaBrainz Blog 
Is there a mechanism to subscribe to be notified when schema changes occur – other than the blog, of course 🙂
It would be nice to be able to request an automated e-mail notification on the date the new schema is published – especially for those of us that have replicated slaves that need to be updated.
Miky: Yes, there is. There is a mailing list called musicbrainz-datafeed — subscribe to this list and you’ll get all the updates you need.