Actually this raised a question for me which I couldn't find answered in any of the threads. I understand that rel=nofollow is intended for certain external links and should not be used for other purposes (specifically not for *internal* links, and not even for keeping the SE's away from duplicate content).
On the other hand, the nofollow attribute is recommended for paid links. All fine and dandy. But what about paid redirect links, like www.mysite.com/adscript.php?redirect=advertisersite.com? Judging from the quote above, this should be a situation where rel=nofollow is endorsed. But strictly speaking, it is also an internal link, so from what I have read so far about using rel=nofollow on internal links, I should be scared using it in this context. Any thoughts on this?