The magic that makes Google tick - ZDNet UK Insight: "Google's vice-president of engineering was in London this week to talk to potential recruits about just what lies behind that search page."
At the end of the article: "One big area of complaints for Google is connected to the growing prominence of commercial search results -- in particular price comparison engines and e-commerce sites. Hölzle is quick to defend Google's performance "on every metric", but admits there is a problem with the Web getting, as he puts it, "more commercial". Even three years ago, he said, the Web had much more of a grass roots feeling to it. "We have thought of having a button saying 'give me less commercial results'," but the company has shied away from implementing this yet."
I've noticed Google getting really bad results for commercially contested searches. The ads are often more relevant. That's bad, and they should fix it. They have a lot of goodwill, but it doesn't last forever.