Lee Odden asks Matt Cutts about clickstreams. Matt made it sound as though generally they had little value:
I’m not going to say definitively that Google doesn’t/won’t use toolbar data (or other signals) in ranking. I think what you were picking up on was my long list of “cons” in data like that.
Regarding cons of using toolbar data, the main reason would be if people were to spoof toolbar data to make a page or domain look more visited than it was. For example, at SES New York, I pointed out that Alexa provides a “Related Links” feature for web sites, and that data had been spammed to show related sites being job sites, poker sites, etc.
This is quite contrary to Mike Grehan's recent article mentioning clickstreams.
Links are good. But you can only get links from other people who have Web sites. What about the millions of end users who don't have sites? The only way they can show a search engine their approval of results' relevancy is by voting with clicks.
I now tend to look at links as a peer group review. If your community thinks your site is the greatest piece of work ever and decides to link to it, you have their vote. End users will decide whether the community was right or wrong.
Is Matt leading us astray, or do you think Google does not use clickstreams at this point? With as sophisticated as some of their algorithms are you would think that they would be able to find some signal out of toolbar data, wouldn't you?