This is a new initiative to prevent comment spam.
There are perhaps many more blogs than I list below mentioning this…
There is a WordPress plugin already developed which implements the nofollow stuff, so you don’t need to wait until there’s an updated wordpress that makes use of it.
Let’s say your normal links inside of your blog comments are of the type:
<a href=”http://will.id.au”>Will’s Domain</a>
Now when Google searches your blog, and sees the link to will.id.au, it will follow that link, and index it.
And through some sort of algorithm, that probably adds some browny points to will.id.au’s PageRank.
Now, this new nofollow attribute is just a bit of extra “fluff” that tells Google and other search engines to not follow links in the comments.
Code as below:
<a href=”http://will.id.au” rel=”nofollow”>Will’s Domain</a>
So when a search engine comes to index any blog webpage, sees a link, rather than following the link to index the linked page, it will just continue on to other links that don’t have the nofollow attribute added.
The hope is by eliminating the incentive for a PageRank boost, we may see a decline in comment spam.
And you can observe the feedback in the blogosphere here