Glad to see that so many feel my point of view is wrong. Always good for a good discussion.
In my opinion, you can not say that they are selling the number 1 spot. Even if studies proof that many people have no idea that some results are paid for. The fact is that they are marked as sponsored links. They are not selling positions in the organic results. You can twist it any way you like it but the fact remains that they are marked as sponsored links. And if you tell somebody that didn't know, they do not get upset. They really don't care.
That Google is doing "research to make that area even more clickable by playing with colors" that is pretty normal. We try to make our website also as effective as possible. That's not a bad thing at all. That´s normal business.
Their search results are not affected by paid links in any way. The presentation of their search results include paid links, but you can not possibly compare those links with the paid links in other websites. Most paid links are far from related, often site wide, they´re sneaked away in parts of the page where people aren't really interested in, not marked as sponsored links, they pass Pagerank, etc. etc. etc. Google's paid links are right in your face, extremely related, marked as sponsored links and they do not pass Pagerank.
They´re not the same thing!!!
If you do paid links the way they do them, you don't get penalized at all.
But the fact is of course, that most link sellers want to do their paid links in such a way that they do pass Pagerank, because that drives the price up. We could just admit that..