Andrew,
Yes clear display of available languages is essential (it is mentioned in the comments of the document I linked to).
When I was working with Lars on i18n we planned to tackle content negotiation after doing all the UI work, but never got to it b/c we ran out of time (and budget). It was not tragic really b/c having content in multiple languages was the exception rather than the rule.
In any case, I would like to see a solution that is not limited to xowiki and the prospect of having thousands urls with unnecessary /lang/pages/ in them on our local site is motivating.
I will try to find out what others have done (e.g. someone recently mentioned that the new version of plone does a good job in this area) and will report back
I do not want this to be hack either Gustaf.
Carl