There's a new beta browser in town, and its name is Firefox
4. Previously available in "Candidate" form, this latest release is a bit more polished and ready for anyone comfortable playing with beta software, which may or may not prove stable (been running fine for us so far).
If Firefox 4 looks eerily familiar, then you must have logged some time with Google's Chrome
browser. Mozilla appears to have taken a few design cues from Chrome, with Firefox 4's UI now sporting tabs at the top, a new Firefox button that replaces the menu bar, and the merging of the stop and reload buttons, to name a few.
Underneath the browser's hood sits a few architectural upgrades, like better HTML5 handling, full WebGL support, native support for WebM video, an experimental Direct2D rendering backend, crash protection, CSS Transitions, and plenty more. Get the full rundown in the release notes here