TieBreaker: who told you such a thing as fact?
Because it is not even close. There have been no studies proving that themed links are *any* more effective than a 100% non-relevant link, or that a non-relevant link can damage you at all.
Anyone that wants to debate that point, I ask you to show it right here in this thread with provable data to back it up.
To date there is no evidence at all of theming.
I realize some of you think the search engines are artificial intelligence of some sort or another, but sorry to say, they are not. Not yet anyway. They are simply programs whose core functions are to spider, index, and search with some extra filters added to look for certain things that are common traits.
Those who wish to use CIRCA as a reference for possibility, that is all it is at this point, a future possibility with nothing to show it is advanced enough yet to be implemented.
As for PageRank, as Granpops pointed out that is simply a mathematical calculation based on links and their originating PR.