MicroSoft Makes Universal Like Button, but Google Invented "Like" Years Before
Microsoft has created a universal "Like" button - like the "Like" button made popular by Facebook - and have put that in the Bing bar. So basically, you can "Like" any web page, even if the page does not have that mechanism built into it.
Google's algorithm measures inbound links from other websites into your own website as a means to determine relevance for a given keyword or phrase. In other words, it measured how 1 website "liked" another website. But we all know that many websites are old and static - their owners don't keep up with references to other websites that they like - so that's why I think Microsoft's new Universal Like Button is a good idea. It gives individuals who don't know how to program a website the ability to cast a vote for a website.
It's speculated that Google has been adding search behavior data into their algorithm, since a click on a link in a search result page is similar to a "Like", and they certainly have enough data to make some decisions on that subject, so they've been adding visitor popularity into the equation for some time.
What's different? Maybe Microsoft has deeper access into Facebook, which is the other bit of news. Using Bing, you can see what websites your facebook friends like.
That raises two interesting points: 1) When you're looking for something, do you expect that your facebook friends have already had the same question and therefore can help you find your answer? and 2) have you checked your privacy settings in Facebook lately? Because your opinion on websites might become more important soon.
Only time will tell if friend's opinions on websites will become a valuable component to the search algorithm, but one thing is clear: Google had it first!