I think a good approach to allow have discussions on SO and SU would be have a "discussion" checkbox, like we have the "community wiki" one. Discussions could appear separated from Questions, and would not have the "accept answer" button. That would be really good!
Stack Overflow and Super User are not discussion forums, they are Q&A sites. Having the checkbox would only encourage people to post the kinds of "questions" they are not supposed to be posting in the first place.
If the team wants to start officially admitting discussion questions, to change the overall mission/vision of the site, then make that explicit in the FAQ and just change the Community Wiki checkbox to say Discussion, because that's basically how people are using it (or attempting to use it) anyway.