The Google blog states
You’ve probably had the experience where you’ve clicked a result and it wasn’t quite what you were looking for. Many times you’ll head right back to Google. Perhaps the result just wasn’t quite right, but sometimes you may dislike the site in general, whether it’s offensive, pornographic or of generally low quality. For times like these, you’ll start seeing a new option to block particular domains from your future search results. Now when you click a result and then return to Google, you’ll find a new link next to “Cached” that reads “Block all example.com results.”
Read between the lines and this option could really impact content farms as people who are a little more discerning can eliminate seeing these results completely. With this option if you really don’t like content farm content you can block associatedcontent.com and Presto! No more craptent. You can then follow that up with all of Demand Media properties like eHow.com, Answerbag.com and more. Imagine the fun.
As for site owner’s ability to truly understanding who sees their sites in search, this could create issues if there is widespread use of the option. That’s just another obstacle for SEO’s to talk around but that is well developed skill already in the search industry.
Of course, not all decisions are permanent as you can go back and manage which sites you have blocked. You will also be told whether results that you blocked would have shown up in the results.
So Google continues to indirectly admit that quality is better left in the hands of the searcher on many levels. The subjective nature of what quality content is obviously escapes the bounds of an ‘algorithm only approach’ when cleansing search results of junk. I suspect Google wouldn’t say this but they are in a bit of a fix when it comes deciding what a true good search result is so they are pushing more of that responsibility to the end user.
What’s your take on how this might impact an SEO’s job? Will people actually block an entire domain from search results or is that too much? Can Google’s algorithm really help make quality decisions for each individual? What’s your take on these efforts to clean up the SERPs?