A shift for some queries - Google nos shows up to four results from a domain under some conditions. This is not just results that have navigational intention, which have already been showing as high as six per domain.
With this iteration, our search results may show:
Up to four web results from each domain (i.e., several domains may have multiple results)
Single-line snippets for the additional results, to keep them compact
As before, we still provide links to results from a variety of domains to ensure people find a diverse set of sources relevant to their searches. However, when our algorithms predict pages from a particular site are likely to be most relevant, it makes sense to provide additional direct links in our search results.
I see this for a lot of terms that are not too competitive. I also have a theory that google uses this as part of their split testing. I think google shows the 4 similar pages and see which gets the most clicks and then shows that page for other terms as well.
I have not seen 4 results for a very competitive term yet