From the Google blog:
We’ve offered a “Similar” feature on results for a while now as a way to discover new, useful sites, but it hasn’t been too visible. Since we’ve been continuously improving this feature and we think it’s really useful, we’re now going to start showing these alternative sites more prominently. Starting this week, for queries where similar sites are likely to be helpful, we’ll display a list of “Pages similar” at the bottom of the results page. For example, this is the list of sites similar to Direct Relief International:
I first became aware of this from Barry Schwartz at Search Engine Land who posted before the official Google announcement and shared a result he produced below
This kind of a result is much more interesting in many respects because looking for the right charity doesn’t feel like you are doing something competitive. Looking for information on search engine and Internet marketing, however, is truly competitive and most folks won’t be too thrilled about Google “advertising” for the competition when someone is searching for your site directly.
So how this new feature is rolled out by Google should be interesting to follow. Imagine one day if Google would ask each business “Who are you similar to?” and starts to find another way to generate revenue. I would hope this would never happen because then that means that the SERP’s were truly “for sale” rather than on merit. Some would say that’s the case today already but I’ll let you fight that out amongst yourselves.