The "U Comment I follow" sign basically means if you place a comment in a certain blog which has that sign, the search engines will follow the author's links, or the links placed on the comment itself. Eventually, this will result in the "commenter" getting a back link.

According to some search engines (like google) they do not follow the links in the comments. A test done revealed otherwise. There are other search engines who say they treat the links like any other link. No matter what they say, I am sure it is sensible to say that disabling the "No follow" will be of mutual benefit to both the owner of the site and the commentor.

So what really does "nofollow" mean ? Google orchestrated this scheme. They observed that spammers are putting up spam comments in a lot of blogs in the hope of getting a lot of back links. (Note that back links help boost ranking in the search engines) To remedy this situation and to aend spamming, Google enforced a "no follow" policy when it comes to comments. This was then followed by other search engines.

The big question is did they succeed ? Unfortunately the answer is no. In fact spamming in websites and blogs are a much more bigger problem today than ever before. Spammers still spam. Word Press founder Matt Mullenweg made a terrific comment on this subject "In theory this should work perfectly, but in practice although all major blogging tools did this two years ago and comment and trackback spam is still 100 times worse now. In hindsight, I don't think nofollow had much of an effect, though I'm still glad we tried it."

So why should you continue to allow "no-follow" after all, it has no effect after. (This is enabled by default) You are better off protecting your blog by activating spam filters. The adverse effect of "no-follow" is that it punishes the commentor with legitimate and sensible comments. As one blogger puts it so nicely, "PUNISH SPAMMERS, NOT BLOGGERS."