Last year, Google announced the launch of encrypted search by default for signed in users. http://www.google.com became https://www.google.com.
Now, Google is expanding this throughout the world. Google software engineer posted a quick message to the company's Inside Search blog:
Several months ago we made a change to our default search experience on google.com — when you’re signed into Google, we add SSL encryption to increase the privacy and security of your web searches. The change encrypts your search queries and our search results page, which is particularly important when you’re using an open, unsecured Internet connection.
We’re now ready to expand this protection, so over the next few weeks we will begin introducing SSL search beyond google.com to our local domains around the globe. As before, we hope that these efforts to expand the use of SSL encryption in our services motivate other companies to adopt SSL more broadly.
Webmasters haven't been real thrilled with the move thus far, as it has affected the referral data that is available in Google Analytics. Google continues to recognize the referrals as organic search, but it no longer repots the query terms that the user searched on to reach the site. Google Analytics now shows aggregate data for visits from keyword: "not provided".