Amit Singhal sigir2006 Google rolled out the most significant change to its core search algorithm a month ago and almost nobody noticed. The change is designed to handle conversation search queries, such as "How do I tie a bow tie?" as well as it handles keyword search queries, such as "White House history." It affects 90% of search results.

The company officially unveiled it to the press yesterday in California:

"It is really big," said Google search executive Amit Singhal.

In fact, Singhal said that what Google has done is the equivalent of switching out the core "engine" of Google's search system for a new one. It's perhaps the most significant change since 2001, according to the Search Engine Land blog.

But the new algorithm, nicknamed "Hummingbird," has been operative for a month now, and yet few noticed. That means it's basically a huge success. The last time Google made a slight tweak to its algorithm ("Panda"), in order to weed out spam and scraper sites, many mainstream web publishers screamed in protest as the search traffic they were used to receiving began plunging.

The fact that few have been screaming tells you that the new algo is doing exactly what Google wanted it to do: Work seamlessly.

You can get more details on conversational search here.

One last thing: At least initially, Hummingbird feels a bit like Facebook's Graph Search, which is designed to handle more abstract or "latent" search queries such as "What movies do my friends like most?," where users do not necessarily know what they are looking for.

Facebook has made a big bet on Graph Search even though may users still remained baffled by it. Google's move into conversational queries suggests the company thinks Facebook may be on to something.