CNN gets accused of blog spam and search engine spamming. CNN on the Spam Attack? from Wired explains how blogger Nick Lewis spotted what he felt was a strange post that was pushing CNN programs. He spotted similar posts on other blogs.
That's the blog spam part, and pretty easy to see why you could think that's a guerrilla PR campaign going on, though CNN denies this in the Wired article. But the search engine spamming part? That's a bit more tricky.
Lewis claims that along with comments were a string of repetitive keywords, which he shows in his explanation of what was spotted. For example:
blog blog blog blog cnn cnn cnn blog blog cnn cnn cnn
He suspects this was placed on this blog to make it seem like he was keyword stuffing, to make his pages attract a spam penalty. The idea is that by doing this, his page would get knocked out of "the first hundred results for the google search 'CNN Blogs'"
Frankly, if he wasn't in the first 10 results, CNN wouldn't even care. No one would -- he's virtually invisible to anyone doing that search. More important, while possibly such a tactic MIGHT work, it was be far easier simply to fire up 10 official CNN blog and do optimization and link building to push whatever anti-CNN sites you disliked out of the top results.