Announced at Opera's Up North Web event today, Opera extensions will allow developers to create new functionality for the browser using open standards (HTML5, CSS, JavaScript) and supported APIs. Opera claims that extensions will be similar to add-ons in other browsers and that its "tried to make it easy to port extensions from certain browsers."
Opera 11 is not yet available to the general public, but according to Opera, the first alpha version should become available for download "soon." After Opera 11 Alpha is out, developers will be able to find the tools and information they need at Dev Opera.
Opera also announced that its web browser for smartphones, Opera Mobile, will come to Android "within a month." Opera Mobile is currently available for Symbian and Windows Mobile smartphones.
The Android version of the application brings two improvements: pinch to zoom, and hardware acceleration, which should bring a faster and more fluid browsing experience on your phone.