From Google blog
As people spend more time on the Internet, they want greater control over who has access to their online communications. Many Internet services use what are known as Secure Sockets Layer (SSL) connections to encrypt information that travels between your computer and their service. Usually recognized by a web address starting with “https” or a browser lock icon, this technology is regularly used by online banking sites and e-commerce websites. Other sites may also implement SSL in a more limited fashion, for example, to help protect your passwords when you enter your login information.
Years ago Google added SSL encryption to products ranging from Gmail to Google Docs and others, and we continue to enable encryption on more services. Like banking and e-commerce sites, Google’s encryption extends beyond login passwords to the entire service. This session-wide encryption is a significant privacy advantage over systems that only encrypt login pages and credit card information. Early this year, we took an important step forward by making SSL the default setting for all Gmail users. And today we’re gradually rolling out a new choice to search more securely at https://www.google.com.
When you search on https://www.google.com, an encrypted connection is created between your browser and Google. This secured channel helps protect your search terms and your search results pages from being intercepted by a third party on your network. The service includes a modified logo to help indicate that you’re searching using SSL and that you may encounter a somewhat different Google search experience, but as always, remember to check the start of the address bar for “https” and your browser lock indicators:
Today’s release comes with a “beta” label for a few reasons. First, it currently covers only the core Google web search product. To help avoid misunderstanding, when you search using SSL, you won’t see links to offerings like Image Search and Maps that, for the most part, don’t support SSL at this time. Also, since SSL connections require additional time to set up the encryption between your browser and the remote web server, your experience with search over SSL might be slightly slower than your regular Google search experience. What won’t change is that you will still get the same great search results.
A few notes to remember: Google will still maintain search data to improve your search quality and to provide better service. Searching over SSL doesn’t reduce the data sent to Google — it only hides that data from third parties who seek it. And clicking on any of the web results, including Google universal search results for unsupported services like Google Images, could take you out of SSL mode. Our hope is that more websites and services will add support for SSL to help create a better and more consistent experience for you.