tarquin wrote:
Let's imagine we've implement it. (yay! :) ) I go to the Swedish Wikipedia to make langlinks, but I make a mistake and mess it up. My user page on se: is blank, because I've never edited there before. How do the people on se: know to find my user page on en: ?
I would say that this isn't "an additional problem" with single sign-on, but a good example of what single sign-on has the potential to solve. The solution is that if we had single sign-on, the system could theoretically detect all of the wikis at which you have a userpage, and automagically link to them on your user pages.
See additional user pages for this user at: [en] [se] [fr].
Right now, there's no guarantee that your id at en is the same person as the same id at se.