The final version of Opera 11 just came out with many new features and enhancements. Improved address bar, Mouse gestures, Tab grouping, Pinned tab, Automatic updates are few of the most noticeable features in the new Opera 11.
One more important feature is its ability to run on external devices. While installing the browser you can select to install it on external devices. Which makes it a portable browser and you can carry it in your Pen Drive with you. Just click on the options button while installing and select install for external device in the next screen.
You can read more about the new features of Opera 11 over here.