Whether comment spam by itself is an application failure or a necessary evil for site allowing rich comments is an open question. However it is reported that in this case vulnerability in WordPress allowed the spammers to actually penetrate the site and modify pages and not just abuse comments.
Additional information:
- Another inconvenient truth: Al Gore's Web site hacked [PC World, Nov 26 2007]
- Blog Link Spam Claims Another Victim: Al Gore [Wired, Nov 27 2007]