Adam Audette has an awesome post on the nofollow:
8 Arguments Against Sculpting PageRank™ with Nofollow
Lets not forget my 5 points written months ago:
Point 1 - We live in a bubble. 99% of the world doesn’t know what nofollow is and probably will never know until the W3 add it as proper markup. So are we to believe that Google has granted SEOs ONLY this special attribute that can help us rank better. No. It is only for Google benefit, not ours.
Point 2 - The theory has not been tested enough and probably can't be properly tested since to many outside forces effect rankings. That is why this 2nd order effect has no bearing. No has proven that spending a few minutes using nofollow helps your website do any better. Google is simply telling you that is will. Google said it was OK to do it, doesn't mean you should or even if it works. Remember the end benefactor of nofollow is Google themselves, NOT your website.
Point 3 - External nofollow: The web and Google's algorithm was built on the concept of linking one document to another. Now we should continue to do this, but in way that does not pass search engine value through the link? Who is benefiting here? The SE algo only. This really goes against why the web was built on links.
Point 4 - Internal nofollow: I simply default to this post by Michael Martinez:
Yes, Virginia, your contact page DOES need 500 links
Point 5 -
PR is not tangible. One page doesn’t have 100
PR credits that you can feel free to divvy up as you like through internal linking. It is not that simple. The point I am trying to make is that these SEOs are trying to say they can sculpt something like
PR. We all know toolbar
PR is crap and internal
PR is not known so…..where does one get off saying they can sculpt something they don't know?