Since my website pagerank increasing this January 2011 from PR 1 to PR 2, my blog is also getting more spam comments. Usually they are from Argentina, Mexico, Brazill, and many other countries in America.
Daily spam comments is about 8 to 16. So, I am thinking, that spam comment must be posted by using a software or script with automation for a wordpress comment box that didn’t use any verification.
And since this February, I tried to use simple Captcha validator for all my blog comment. Finally, none of the spam comments is comming again to my blog.
If you want to try this Captcha Plugin for your WordPress, you can try to search for “SI CAPTCHA Anti-Spam” which is developed by Mike Challis