The nofollow attribute is one more thing to check for on all the text link advertisements you purchase. Shady webmasters may start using the rel=”nofollow” attribute on their link pages so the major search engines won’t follow the links off of their site.

This new attribute was primarily added to fight blog spamming, but I can already bet it will be abused. Please do you due diligence and report any sellers that try to use this tag on your links to LinkAdage.

BTW: It’ll be interesting to see the shift in the SERPs when sites with lots of blog links start to drop like rocks.
More information on no follow can be found here: http://www.sixapart.com/pronet/2005/01/introduction_to.asp