I strictly do not use the "nofollow" attribute and I will never do. I use an technique that does not pass
PR to an external site, but it is not the best semantical linking option. Also not the best accessibility option.
For example look at this link:
Webnauts | Drupal Association
Now, I decided to replace this technique with microformats, which all SE began supporting them at a certain extent.
I am planning now to use the following:
For linking to relevant authority resources:
rev="vote-for".
For linking to other resources:
rev="vote-abstain".
For affiliate links:
rev="vote-against".
I was using them last year and for a very long time, and I never experienced any problems.
Do you see any problems with this option?