I’ve done some integration of OpenID selector into MediaWiki OpenID extension and some fixing/improvements of the latter.
You can see changes on TPr, MWW and SharingButtons.
Next week will take a look into checking it back in. Still need to figure out if I can check in BSD code (selector) into MW tree or need to write something similar (I’m even thinking about creating something like SharingButtons, but for OpenID providers) and release with GPL.