On a more serious note though, its nice to see Google validate our assertion, that un-modified Google search results are getting poorer and poorer. Not that they would actually say it directly like that of course. Now lets see if they are willing to drop over a million crappy sites out of their index ...
So you go to start a company and you say that you believe the search experience is getting worse and worse. That you believe the leader in the market place is fighting a losing battle of trying to algorithmically determine relevance in a world where humans will actively work to subvert the algorithms. That the world would be a better place if a more customizable search experience existed.
A common response is "Well if this is such an important idea they would already be doing it."
So as an entrepreneur you deal with the naysayers and you build something which other people have "... been clamoring for a blacklist for years" and yet has never materialized. And you put it out into the market.
Right up until you deliver your product, nobody knows who is 'right' in this back and forth. It is all academic. You've built the best product you know how to build, you offer it up to the world, and when you ship the debate stops being academic and starts becoming empirical.
When the market leader adds features that mimic ones you've launched with several months ago, it can be simply timing (they may have been going to do it all along and it just happens that they did it now), it can be a response, it can be random I suppose. Regardless of why they did it, it seems to be an unequivocal damnation of pure algorithmic search.
As one of Blekko's founding concepts was that the search experience can be made better by human curation, I choose to interpret it as validation. Not that I expect Google to join in and adopt the "web search bill of rights" anytime soon of course.
Similarly, I don't see the ability to choose whether you're doing an image search or a news search as a condemnation of algorithmic search either.
Now they have backed off on that, with reasoning that it is really not truly possible given that the search "Sony XBR TV" might be you are looking for the manual for the TV or to buy the TV or something which isn't known, but the goal is always to have the result you're looking for on the first page. That has been their target and promise for years.
So by creating a feature, and putting it into production, to "block sites" it suggests to me that they are saying "Hey, we know our algorithm is failing and we have given up (perhaps temporarily) trying to fix it. We know it will put sites you don't want to see into the first page. Here is a manual tool to weed those out."
It seems like something of a philosophy change at least. Perhaps Matt will chime in.
Look at this search - "how to get pregnant" - that exact phrase gets 550K searches on google a month. My wife and I did this search last week actually.
Blekko's top 3 results are 1. get-pregnant-guide.com which is an affiliate site that points to pregnancymiracle.com - one of those crappy ebook sites where they have a bunch of testimonials and ask for you to pay $39.95 for their guide, 2. a digg post that has 1 digg which points to a hubpages article that no longer exists, 3. purelyfitness.com/how-to-get-pregnant which is also an affiliate site that points to pregnancymiracle.com.
Google's top sites are the mayoclinic.com, mahalo.com, and howtogetpregnant.net. The least useful to me was howtogetpregnant.net, but they still gave a decent amount free advice. I actually found Mahalo to be the most informative which is blocked from your results. I find Calacanis just as annoying as everyone else, but this page was more beneficial to me than even the mayoclinic.
I'm not sure if "Human curation" is the concept I'd grope for here.
What I'd like is search that uses a "larger context" - what I've searched-for and accepted/rejected, what those similar to me have searched-for and accepted/rejected etc. Being able to implicitly use a lot of information is crucial because there aren't going to be enough curators to everything ever.
Google is already using an incredible amount of implicit information and I expect them to use more.
What I see opportunity as really, is more like "self-curation" than some finite stable of curators. What would be cool is a system to let me keep my list of likes and search-finds - essentially my entire preference-system - and let me edit and send the whole thing to different search providers as well as to friends.
Personally I prefer knowing that those sites are in the index, but don't show up unless I purposefully widen my search to include them (or they appear so low in rankings that it achieves the same effect).
"In addition, while we’re not currently using the domains people block as a signal in ranking, we’ll look at the data and see whether it would be useful as we continue to evaluate and improve our search results in the future."