This is more or less the right list; though it would also be appropriate to mediawiki-l , the list for all mediawiki developers.
You might also take a look at what the Identity Commons is doing. I don't understand all of the standards involved, but it involves a richer API than just distributed authentication... http://idcommons.net/technology.html
+sj+ _ _ :-------.-.--------.--.--------.-.--------.--.--------[...]