Lee Odden of TopRank wrote about his conversations with Matt in which the Google engineer answers queries related to Google's ranking tactics. Lee's queries are as follows-
1. Does Google currently use toolbar data for rankings?
2. What do you see as the pros and cons of using such data for rankings?
3. Can you describe any scenario where information from a downloaded application from Google might be used in some way for ranking web pages?
4. If Google does not employ toolbar or other user data for rankings and another search engine does, could that provide the other search engine an advantage?
Matt's reply is as follows-
"In general, when someone asks me the question “Do you use signal X in rankings?” a good way to answer that question is usually to say that while we don’t comment specifically on most of the factors that we use in ranking, it’s wise not to rule something out absolutely.
Meta tags got a bad rap in the early days of search engines because a few people abused them heavily. As a result Google doesn’t use meta tags much in ranking documents. But I’ve learned not to say “We would never use meta tags” because it’s not wise to preclude using any particular signal. So I’m not going to say definitively that Google doesn’t/won’t use toolbar data (or other signals) in ranking.
Given the attention that people have given to PageRank, which is in Google’s toolbar, you can see how I’d feel about using toolbar data. I’m not going to say whether Google uses a particular signal in our ranking; I just wanted to communicate some of the potential problems in using things like toolbar data."
It's good to have Matt explain things so elaborately. From time to such honest clarifications clear the dark clouds around search engine results.