You know, I think, that, if you're logged in Google, you can promote and remove a result from the serp, and write a comment about a website on serp. But: the comments are shown only by you, if logged in; the websites promoted- or removed- can be seen only by you, if logged in. I think that Google doesn't introduce a feature without a reason. I think that Google is collecting now a lot of data with this feature. How will Google use in future these data, in your opinion? And what effects will this feature have on the search results?
Google will likely never use this in any way, shape, or form to influence how a page ranks for a particular keyword phrase... It is TOTALLY susceptable to spam and would allow spammers to manipulate the SERPs by voting down competitors. They do this for user convenience. For instance, if I search and get 100 results on page 1, I may go through them looking for something. If I determine that the 1st one is NOT what I'm looking for I can remove it so that I don't keep clicking on the same links that I have already eliminated. When I find a result that looks really good then I can promote it to the top of the listings... It allows you to customize your results as you view them... It's a usability feature... and IMO would never be used as a ranking factor.
I agree that this feature will not be used for the ranking. But... is it not more usable for the users bookmarking the results that he find good for his searches?
I hope Google never use it for ranking; imagine having thousands of cheap workers working for you all adding you to rank you higher. It would mean that certain parts of the world would become world leaders in optimisation.