You may be aware that Google updated their algorithm last year to penalise sites that have a lot of paid links pointing to them. Many high profiles sites saw a drop in PageRank because the sites that link to them were being heavily penalised for selling links. But when is a link classed as a paid link? The most obvious examples are TextLinkAds (who now don’t even rank well in Google results for a search for their exact name — other than as a sponsored link). But hey, aren’t AdWords paid links? Of course they are. Google just doesn’t like the competition. Yahoo has been selling links in the Yahoo directory since before Google was even live (but thats OK apparently).