User blog comment:Rappy 4187/Technical Update: January 23, 2013/@comment-3030984-20130122173649/@comment-957747-20130122185533

The way MediaWiki messages have worked in the navigation was confusing to users. For instance, if I put

*Places

into my navigation, I would see "Places on this wiki" - the text of MediaWiki:Places. After this code release, MediaWiki messages will only transclude into the navigation if preceded with MediaWiki:. So if I wanted "Places on this wiki" to show, I'd have to enter:

*MediaWiki:Places

If, in your example, we wanted to link to a specific MediaWiki page, you'd have to wrap it in. But, as you eluded to above, this would be the rarer case.