Google started to add last month tips that promote services like Blogger, Google Calendar and Picasa. This form of undisclosed advertising generated a lot of buzz and now the tips are gone. The tips were also too frequent and almost annoying, because they appeared at the top of the search results pages for every query that contained: "blog", "calendar", "photo sharing" - and that includes: "yahoo calendar", "bloglines".
It's nice to see that Google is receptive and understands that practices common for others are not consistent with Google's philosophy. And in case Google needs to be reminded about their principles, here's an excerpt from a page titled "Why we sell advertising, not search results":
In a world where everything seems to be for sale, why can't advertisers buy better position in our search results? The answer is simple. We believe you should be able to trust what you find using Google. It may seem odd for a search engine to speak about the integrity of its results. But like a news organization, we believe we have an obligation to present information as objectively as possible. That's why we don't bias our search results based on what people are willing to pay. (...)
And while we believe relevant ads can be as useful as actual search results, we don't want anyone to be confused about which is which. (...) Some online services don't believe the distinction between search results and advertising is all that important. We do.