Got my first resume via comment spam yesterday!  Not quite sure, but I really don't think that is a good idea ... but maybe Getchen or Heather would have another view point.  I know the idea behind comment spam is to get your search results higher in the ranks of search engines (well usually, Casey actually had another point with his experiment), but come on ... resumes? 

Last week in David's blog he points to an interview with a comment spammer, which is an interesting read if you have the time and interest.  Seems there are several points in the blogging system that allows these comment spammers to get paid big money for their type of “search engine optimization”.  Some of the things that seem to lead to comment spamming (that interview reminds me of Tom Hanks in You've got mail “It's not personal, it's business ... IT'S NOT PERSONAL, IT'S BUSINESS“) ... unfortunately blogs usually are a personal thing...

• It is legal (not sure if this one should be touched or not, but still it is seems to be the starting point for most arguments in comment spamming)
• Importance of search engines (not much we can do about this one)
• Manner in which search engines determine their rankings of search results (this is proprietary and therefore pretty much untouchable)
• Demand and willingness to spend money to be at the top of the search results (seems to be a sort of marketing expense?)
• “Badly configured proxy servers“ used to help hide the real source of the spam (this one also leads to the truth about how few servers are up-to-date on their patches and are configured correctly - which means administrators need to be aware and knowledgeable about the complete system)
• Referral links available publicly (will show up in search engine indexes) and trackback type functionality of web sites (Added after Casey brought this one up)
• The openness and good nature of the blogging community and the software that makes it possible (This is the part where if you don't allow feed back or comments you know you don't get spammed ... but to me that defeats part of the purpose of blogging, but maybe I am too open and too good natured - who know)
• Blogging sites that don't fix or update their software when a fix is available (sort of the flip side of the server administrator problem, this one is the application administrator's problem)

The last couple of items seem to be the only one that can easily be fixed.  Even though Captcha can be beaten (by the smart ones), I do think it is one of the least obtrusive ways to limit the current comment spammers ... at least until a better solution is provided.