You and I have had a couple of conversations about this Jaan. While I have "experimented" with internal nofollow I can't say that I have any definitive "proof" to offer short of my observations and opinions. Based upon those, I've personally chosen not to use them.

I really think that the biggest mistake that gets made when implementing the nofollow internally is that the focus gets put on where to NOT flow PR rather than where, and just as importanly, how to send it. Blocking pages can actually do you more harm than good IMO. An important thing to remember is that every time you block a page using the nofollow you're also lessening the value of all the links that are on the blocked page.

Another thing is that seems to get overlooked is that PR is strictly a Google thing yet the nofollow affects what the other SE's see and do as well. While trying to "sculpt" for Google you can easily negatively affect a site or page with regards to the other SE's.

Personally, I'd rather focus on doing a better job of targeting pages internally, not by restricting access or flow, but by improving the way in which it does flow. Using pages which may not neccessarily be most useful until a visitor actually reaches the site to their benefit and my advantage.

ETA... It is just another tool available and it's not using it that *can* create problems, it's how.

Dave

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