Google's Chuck Rosenberg, Similar Images team, explains, "Using it you can now find images that look like an existing result simply by clicking on a link. Using visual similarity, you don't have to refine the text of your search, instead, you can just click on the link of an image you like."
In other words, lets say you perform a search for "lions". Most of the image results show the king of the jungle, a.k.a., the feline version of a lion. Above all the image results, however, are several links. The first one is exactly the type of lion I was actually looking for: those that play football in Detroit. In this case, if you wanted images associated with the Detroit Lions, it was a simple click away from the general search for "lions".
The other update is called Google News Timeline. Andy Hertzfeld, Google News Timeline team, explains, "Google News Timeline organizes information chronologically by presenting results from Google News and other data sources on a zoomable, graphical timeline. You can navigate through time by dragging the timeline, setting the time scale to days, weeks, months, years, or decades, or just including a time period in your query."
It's a pretty neat tool. If you're looking for information that you know occurred in a specific timeframe, you can quickly see how it unfolded across different news sources during that period. Check out this example result here.