In the first week of my link building class (Flash video), I go over a spectrum of "link types," based on the idea that search engines really want to see natural links of pure love, those that are created by web authors who really like the web resource (site, page) they're linking to.
There's another type of link, though, that probably counts for just as much in boosting the authority of a web site, natural links of pure hate. It's just possible that these are actually easier to get.
When a blogger cleverly links to Microsoft's web site with words like "evil empire" in the text of the link, they think they're sticking it to the man, but they're actually passing link love to the man. Which makes it easier for Microsoft to put more pages into search results... and still hasn't made Microsoft the #1 result for 'evil empire.'
When right-wing loons link to Michael Moore's web site with "miserable failure" in the link, they're actually helping Mr. Moore's cause by passing PageRank to his web site. Which makes it easier for him to spread the word about just how nasty US elections actually are and how the greatest losses in the Iraq war are felt by ordinary Iraqi civilians.
But I digress... these are just a couple examples of bloggers helping their enemies in search engine rankings. I could go on for days. Link condoms, anyone? Or are all bloggers just a bunch of morons? Is the blogosphere full of idiots? It's possible...