i think newcomers that don't use search functions are probably thinking that the community they sign up to (CM.O in this case) will be nice and welcome them, therefore they will make a thread without thinking twice. i don't think there is a way to fully avoid this. maybe sometimes people just want to say hi. if you could make it clear to a newcomer that you don't want threads like this, maybe it would stop them somewhat. (although personally it doesn't bother me.)
bryfaces idea is probably the most viable. a display, something in your face.
OK. so current users don't want to see this on their front page for whatever reason. how about a page you are directed to right after signing up? a page just like the one george has created however embedded into CM.O.
whilst i do think the idea of a link to links is a good idea, i don't think it will preserve itself for long. for instance this is the only thread it is currently mentioned in and it lacks of an easy to find title, the URL is almost useless and makes no sense. this will be buried within weeks if not days.