We've discussed this in the past and as someone who has been trying to go back and weed out all the old 11.04 questions that were asked before release I am convinced that supporting ubuntu+1 questions is a Sisyphean task.
As I mention in the post I linked, ideally as the release comes closer questions should become more and more "long lived" as nothing is changing as much. However we're neither at Beta or UI freeze, so questions tend to be useful for only that short amount of time.
user606723 says that maybe we can blow them away post-release, but that doesn't work either as by the time it's released we have a mix of useful questions already, as well as a bunch of "too localized" stuff. What needs to happen is we need to look at the tags and then decide for each one. This is a lot of work, and we always miss them (I find and flag old 11.04 alpha questions nearly every week, still!)
As far as "if it is it's probably a dupe, and I'd rather have that discussion first." goes, the format of this site doesn't really lend itself well to having discussions, but either way when it's released people will ask if it's a bug anyway, so we're likely doomed there.
I am in favor of having these sorts of questions handled in the subforum on ubuntuforums.org because they do end up closing the subforum at the end of the cycle and whatever is broken at that time will be looked at by people who might be able to help better than we can.
I know it's not ideal but I tend to err on the side of "keep it strict and tight" because the lesser of evils to me seems to be to have people asking when it's released or close to final, as opposed to trying to deal with things that are changing too quickly.
I would love if we had many more people editing questions to remain relevant but it seems to me that we can do a better job documenting the stable releases than grinding away at this problem.