As a Chrome user, you probably know the Omnibox, the combined search and address bar in Chrome.
But you probably did not notice the difference in search when you signed into Google and when you did not sign into Google.
If you sign into Google, the search is encrypted, i.e., the search is sent through https. But if you are not signed in, your search will be sent through plain HTTP, which means your search can be easily monitored/intercepted by others.
So, this can be a privacy concern for some users.
Of course, you can always get encrypted search through: https://encrypted.google.com. But for Chrome users, a lot of searches are sent directly through the Omnibox.
Encrypted search can protect your privacy. Actually, Firefox sent encrypted search since Firefox 14 in last July; Safari started to send encrypted search in last September.
Finally, Chrome 25 (now is in beta) starts to send encrypted for all users (not just the signed-in users).
You can try this version from the official Chrome beta page: https://www.google.com/intl/en/chrome/browser/beta.html
Enjoy your encrypted search.