Mozilla outs Firefox 4 beta

Shiny new tabs
It’s based on the Gecko 2.0 engine and offers quite a few tweaks and all-new features. The new version is supposedly more responsive, secure and less likely to crash when plugins fail.
Panorama is a relative novelty and you might have already seen it in action some time ago, when it was still called Candy Tabs. It lets users navigate through numerous tabs in grid view, which should come in handy in a number of scenarios.
The beta also offers improved support for CSS transitions, HTML5 and experimental Direct2D rendering backend.
You can check out the full release notes here.