Firefox 2.0 - RC3 at the time this was written - has been released and is available for download. There's some scuttlebutt about whether Mozilla meant to offer up the new version or whether it was leaked. Regardless, the new version is here and offers several new features and enhancements over Firefox 1.5. For a quick list of what I think the most important enhancements are, read on!
New built-in phishing protection, turned on by default, warns you if you browse to a site Firefox 2.0 suspects to be malicious or a Web forgery. In order to determine if a site is malicious Firefox checks the sites you browse against a list of known phishing sites. This list of sites is automatically updated to keep Firefox 2.0 users protected. Not so much a feature for the technically savvy, phishing protection will be most appreciated by users less familiar with the many pitfalls of Web browsing.
Better Tabbed Browsing
Tabbed browsing is now default behavior in Firefox 2.0. When clicking new links Web pages will be loaded in a new tab unless you disable this feature. There's also a new tab selector drop-down that displays a list of each Web page you have open. Furthermore, when you open more tabs than your screen can display, Firefox 2.0 displays an arrow on the left and right of the tab bar. Clicking either arrow allows you to scroll through the tab bar so you can see all the tabs you have open. As if that wasn't enough the history menu now keeps track of all recently closed tabs. Close one of your tabs accidentally and forget the URL? No problem, access the History menu's "Recently Closed Tabs" list and your back in business.
Inline Spell Checking
Web forms now support inline spell checking on textarea form controls. For some reason, regular text boxes do not support this feature.
Updates to the extension system
There are some new security improvements to the extensions system but I haven't found much more info than this. During installation, several of my plugins were flagged as not compatible with 2.0. Fortunately, the installer includes a feature that checks for updates to your installed extensions, a process that found compatible versions of some of my plugins.