I've been definite in my anti-necromancy stance for some years now, since it started happening. It's not a cardinal sin, nor is it the most disruptive habit, but I think it's annoying enough.
There has been a rule against it for a while now. The theory is that if you really need to continue a discussion from 6 months ago or more, you should summarise and continue the discussion in a new topic. We're coders for the most part right? whatever happened to modularity? .
I did close a few threads that were resurrected, but it seemed rather counter-productive as the damage (if you can call it that) was done by the time I closed the post.
So, I guess I think auto-closing of posts after a suitable time would be useful.