pageoneresults - 1:10 pm on Nov 29, 2010 (gmt 0)
I emailed a dozen of them and only two responded. Both said they were aware that PR is still lost through the nofollow link. Both said "better safe than sorry" somewhere in the email.
Were these naturally occurring links to begin with? Or, were they solicited? I ask because it is all relative in this instance. Certain industries are going to have a much higher rate of this type of stuff because they are SEO saturated. Other industries have no clue what nofollow is.
If half the sites linking to you have the nofollow attribute, I'd guess you were soliciting the wrong type folks for links - if that is the case.
If the links are naturally occurring, I wouldn't worry about what percentage is nofollow vs dofollow.
After almost 15 years in this industry, I'm still surprised at the amount of time and effort spent on link development. If I told you I've managed one site now for 6+ years and we've never, ever, solicited a link, what would you say? And, we rank 1-3 for our most popular single word search terms, without all the damn links! All the competitors around us are constantly caught up in the link chasing game.
We have better things to do with our time instead of chasing fake currency. ;)