I am trying to get more steam behind proper support of our extension community from both the mediawiki documentation and core developers.
http://www.mediawiki.org/wiki/Manual:Extension_support
This is a landing page for support, the idea is that core developers will document changes that affect extension devs in the subpages for each version, both in new classes/functions/variables exttensions should be using now (Upgrading), and if they use the new functions what they should be using if they want to support a version or two back (Downgrading). These should not read as full guides or documentation, but point people in the right direction to class reference pages and Manual: pages where more extensive documentation can be outlined.
As time moves on, your documentation with supporting new versions will become the support docs for older versions, so not only does it help our current authors stay current, but it helps in bringing much older extensions (often unmaintained) up to date, and helps extension authors retain support a bit behind the bleeding edge.
I hope that others around can show their support and help out with this task now and in the future.
Thanks! Olivier Finlay Beaton