No announcement or fanfare.
The changes are called SearchWiki and they enable you as a search user to customize the search results you see. You can re-rank, delete, add, and comment on search results. If you don't like the way your search results are listed, you can give negative votes to the pages you don't like and positive votes to pages you think deserve a higher rank.
The votes and changes you make will only appear on your Google results pages; they won't influence the result that other people see when doing a similiar search on their computers. However, it is hard to imagine that Google won't take note of this valuable user input, especially if they see patterns emerging for individual websites. I think this information will find its way into the search algorithm before very long.
So what are the implications to you as a content website or blog owner?
If you create great content it will get positive votes. If you create average or poor content you will get negative votes. In the medium term this will feed back into Google's pagerank algorithm and will determine how much traffic your site receives.
Here is Google's own video describing how SearchWiki works: