As I mentioned in a prior email, I have been converting UsabilityInitiative/* extensions to work with ResourceLoader, and in the process removing their dependency on UsabilityInitiative.php. Some of these extensions were not really using any functionality in UsabilityInitiative.php, so their "conversion" was more like cleanup and removing a line that included it unnecessarily. The remaining extensions (WikiEditor, Vector, ClickTracking and PrefStats) are now only compatible with MediaWiki 1.17 because they depend on ResourceLoader functionality.
I'm hoping these extensions, especially WikiEditor and Vector can be examples of how to make use of ResourceLoader in extensions. Please note: if you are working on code that is aimed at deployment this year, you should not depend on ResourceLoader. We hope to have it running live in November, but that's not a guarantee.
Please see the README for UsabilityInitiative (http://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/UsabilityInitiati...) which you will notice ends in calling out that these extensions should be moved. I've already moved Vector and WikiEditor, and the remaining ones will likely be moved soon if there are no objections.
This should put the last nail in the coffin for UsabilityInitiative. (the extension that is, the grant has been over for ages!)
- Trevor