From the article intro: "There some discussion going on in the webmaster/SEO community that Google may have de-indexed some free web directories.
Barry Schwartz at Search Engine Roundtable points to a WebmasterWorld forum thread on the subject.
The thread begins with a post from user Sunnyujjawal, who says:
"While checking some sites links I found 50% free submission directories are out of G now.
Will Google count such links in negative SEO or unnatural linking?
Schwartz concurs that about 50% of the ones he searched for did not have listings."