While Firefox 2.0 isn't expected for a final release until early 2007, the second Beta of Mozilla Firefox 2.0 (Bon Echo) has been released. Of the many changes in this beta release include an updated Firefox 2 theme and visual effects, built-in phishing detector, enhanced search capabilities, improved tabbed browsing, browser resume session, preview/subscribe to RSS feeds, in-line spell checker, live titles, and improved add-on manager. The various Beta packages can be downloaded from Mozilla.
http://www.mozilla.org/projects/bonecho/all-beta.html