I remember Jeff saying, when they announced Server Fault, that it was going to be possible to move questions between sites. I'd find that feature very nice as since then I've found at least 10 questions on either site that belonged to the other one.
It might be useful to have a way to immediately move your own question before there are upvoted answers - similar conditions as for deleting your own question.
It happens too often that a question is voted on to belong to another site, but at the same time downvoted too. This could be prevented by immediately moving the question. Especially newbies not aware of the other sites will profit by this.
Could this not be sone wholesale based on a tag?
If we can vote a tag as belonging to another site like "Server2008" then if someone uses it on Stack Overflow they are prompted to move the question at the point of entry?
It can say "Is this a programming question? if not it may belong one one of the sister sites...bla bla".