I've just added a tag wiki for myslq, essentially copying the text from SO's mysql tag wiki, leaving out the popular questions section as they are SO questions as felt that we should do something similar with PSE questions, but didn't bother to actually do it.
I'm wondering if it would be of any value to automate the process (ask our overlords to do it for us) and just link tag wikis across SE, or at least between SO and PSE, in which same tags will most probably refer to the same subject. We have a few empty tag wikis for popular (or somewhat popular) tags, i.e. oracle, that have great and peer reviewed info on their SO wikis.
And if we can't automate it, would it be generally acceptable to just copy paste the info from SO? That would give the copy paster 4 points (2 for excerpt and 2 for body) and that somehow feels wrong. (although I'm expecting my 4 points for my hard work at the mysql tag wiki soon, people)
edit
I got my 4 points (and a badge) for the mysql tag. And I'm now fighting the urge to copy paste info on all our empty tag wikis...