My main with stack overflow, as it gets older, is answer rot. A couple of times I have come across answers which have become out of date, but it is non obvious to me the best way to reopen the question (I, along with most readers don't have the karma to edit questions / answers )
Maybe write a comment, "This is out of date. Can someone update this?" You might even want to flag the question. You can also add a new answer and downvote the obsolete answer. Getting enough points to edit questions is pretty easy.
Everyone can edit questions and answers (if you don't have the full-on privilege yet, your edit will go in a queue and be vetted by more experienced users).
