It appears that Yahoo has started to group results together by indenting listings from the same domain under the first search listing. For example, a search on search engine land at Yahoo returns these two results, the second being indented.
Google is also conducting some testing with their search listings. Tom Critchlow at the Distilled blog noticed Google is giving him the option to sort the Google web results by date or by relevance. I personally do not see it, but Tom shared a screen shot of it in action:
Notice at the top right it says “Sorted by relevance” as the default, but gives Tom an option to “Sort top results by date.” This sorting feature is not new to Google because we see it on Google News and Google Blog Search, to name a few. But it is very unusual to see this sorting option on Google Web Search.
Tom shared how the URL parameters change based on triggering the sort option:
Sort by relevance (regular Google results):
Sort by date (fresh Google results):
In addition, I do not see sorting options at Google Advanced Search. I do see a way to limit by date range, but that is more of a “filter” as opposed to a “sort.”