Anthere-
http://bugzilla.wikipedia.org/show_bug.cgi?id=708 Erik proposed himself to write it for release 1.4. What is this status ?
I'll code it soon. The biggest open question is what syntax to use. I think I'll go for [[Sidebar:Wiktionary:Bla]] (where "Sidebar:" would have to be localizable).
If I understand him correctly, Brion has argued that these links should be automagically displayed if there is an article with the same title on a sister project wiki. That would be nice, but harder to implement.
Regards,
Erik