I'm looking into this a bit now. It's not a clearcut situation, in that SO has a license that allows copying. Jeff, drop me an email and let's talk about it more (I followed you on Twitter so you can DM me).

The specific example at http://webmasters.stackexchange.com/questions/5385/page-appe... is ranking SO at #1 for me now, but if you send some more examples I'm happy to chat with people in the search quality team about this.