If full urls are displayed, auto inserting a "rel=nofollow" will help discourage seo-types. I know that for security purposes, a number of places like the Internet Storm Center use "hxxp" to ensure they can't accidentally be clicked upon. Howerver, a user who chooses to go there can easily copy it.
Working in the I.T. security / reseller business, we get to see so many malware attacks that somehow battling rogue links would seem to be very important.