Mozilla Firefox 9.0 isn't officially due out until tomorrow, but the download is already available from Firefox's website. (The home page still lists version 8.0.1 as the most recent, so you'll have to hit the source links below for the new version.) The update includes Type Inference, a feature that Mozilla says can boost JavaScript performance by up to 30%, and improved theme integration and two finger swipe navigation for OS X Lion. Finally, there's the usual host of bug fixes and stability improvements. 

Mozilla started a new rapid release development cycle this year that matches Google's development pace for Chrome — it plans to release a new version of Firefox every six weeks — and this release comes right on schedule. In 2011 alone Firefox will have moved from version 5.0 to 9.0, and if it continues with the current labeling scheme, we'll be looking at Firefox 17 by the end of next year.