A thread that I think is interesting enough to promote to a news article. Usually they will be edited (or even completely rewritten) by me to make them suitable for use on the news page. If I completely rewrite something, I usually quote the original post at the bottom.
Some posts might be interesting, but they're just a couple of words and a URL. In those cases, I don't usually promote them as I'd have to write the entire thing. I just start from fresh myself.