Mozilla launches
3.1 beta version of Browser Firefox, It will provide
Download for Free Smart Location Bar(with restricted access)
Web standards improvements in the Gecko layout engine
Support for CSS 2.1 and CSS 3 properties
Tab-switching shortcut that shows previews of the tab you’re switching to
Support for new web technologies such as the video and audio elements,
W3C Geolocation API,
JavaScript query selectors,
Web worker threads, SVG transforms and offline applications
Mozilla developers quoted that :Users who download the beta should not expect their
add-ons to work properly. you can provide
feedback to Mozilla you can
file a bug too.
Firefox 3.1 beta screenshot:

Add-on Support Screenshot:

Known issues in firefox 3.1 : Copied From
Mozilla 3.1 release noteThis list covers some of the known problems with Firefox 3.1 Beta 1. Please read this before reporting any new bugs.
All SystemsCertain client certificates will fail to install when downloaded from a CA (see
bug 453227)
The “Feed” tab is not present in the page info window (see
bug 458579)
Preferences set using the page info window do not work properly (see
bug 459157)
Microsoft Windows
In some cases, the migration dialog will not launch after successfully installing Firefox for the first time (see
bug 459082)
Mac OS X
On PPC Macs, viewing a Ogg video, displayed in a