Admins have been doing a decent, timely job taking down the spam that comes up in the Discussion section. But it is an eyesore for any period of time and there seems to be more and more of it. And there is an easy solution: a small karma requirement for discussion section posts. I think 5 would about right. A reasonable, literate person can get 5 karma pretty easily. "Hi, I'm new" usually does it. That plus a half-way insightful comment about something almost definitely will. This would screen out the spammers. As for the occasional genuine user that posts in discussion before commenting at all, I don't know how many there have been but my sense is that delaying them from posting until they can get five upvotes is almost certainly a good thing.
Thoughts? Or is changing this actually a difficult task that requires rewriting the site's code and that's why it hasn't been done already?
Then let me make it as easy as possible:
Note that this is a bit of a hack; the right thing to do is to replace the karma_to_post global variable with a member of Subreddit, and make some UI for adjusting it. One side-effect of doing it this way is that the message users get when they don't have enough karma (from r2/r2/templates/newlink.html:81) always says they need 20, regardless of which section they tried to post to.
It looks like wezm has followed your suggestion, with extra hackishness - he added a new global variable.