Rand Fishkin of SEOmoz recently posted on the issue of rel=nofollow changes at Google, which prevent Pagerank being saved and sent through to the other links on the page (sculpting). The post comes after a blog entry by Matt Cutts on the topic.
I agree that it can be frustrating when Google reverses direction, but I've always maintained my belief that using rel=nofollow to sculpt Pagerank was a bad idea and counter to the idea of Pagerank in itself. I just plain don't like rel=nofollow, unless it used as a purely protective measure for potentially spammy UGC (User Generated Content).
Rand says one or two things that I disagree with:
"I'm saddened to say that given this change, we, as SEOs, are going to have to also recommend the best practice that comments (in all forms of UGC) no longer accept links ... Comments that contain links, unfortunately, will actively detract from a site's ability to get pages indexed (as they'll pull away link juice from the places that need it)"
The web has changed, and the notion of preserving Pagerank that existing in the early 2000's is gone. What matters today is not so much the Pagerank of pages, but how pages are intertwined, themed or fused with pages on the same topic or closely related topics.
A blanket statement that links in UGC should be ignored is a terrible idea. UGC often introduces some quality links that can actually add to the ranking potential of the page. Granted however, there is a risk of spam links causing a negative impact on rankings, but sites should be sufficiently moderated to prevent such links. If quality control and moderating isn't in place, then how trustworthy is the site anyway? Besides, rel=nofollow can still be used. Worrying about saving the Pagerank is not a big thing in my view.
"From now on, if you wish to sculpt PageRank, you'll want to use one of the following classic PR sculpting methodologies:"
And Rand goes on to list some of the old-school methodologies to prevent links being displayed directly on the page. There are a couple of problems with these trickery ideas:
I agree with Rand in that this a pretty big shift in how Google handles PR flow, but I would certainly say that it was a very predictable move. In hindsight, I'm very glad that my team has never adopted the notion of PR sculpting with rel=nofollow. We have other more practical methods.
PS. My blog CMS is a custom solution and I haven't gotten around to implementing links in comments yet, but I do plan on doing it. When I do, the links probably won't use rel=nofollow (I haven't thought much about it yet), but I will be removing spam links, so I'm not too worried.