Windows/Mac/Linux: Opera's letting us have a look at how extensions will work in their browser with the Opera 11 Alpha. It's very Chrome-like and convenient, and the browser itself has picked up a few improvements in this version too.
Outside of extensions, Opera is citing speed and performance improvements in this version, and we're eager to give that a test, based on previous surprises. There's also a better mail panel, tweaked bookmarks management and more support for HTML5 web features.
Opera 11 is a free download, in alpha, for Windows, Mac and Linux systems. Give us your verdict of the browser and its extensions, knowing that it's very early, in the comments.