As the firefox team said, the browser rely on a couple of major architecture improvements – Electrolysis and Layers should make the browser much more responsive and is expected to improve both the performance and the graphics (including scrolling, zooming, animations). Pinch-zooming is supported too if it’s installed on a device that capable to handle Multitouch. There is still no support for Flash, though, even on Android 2.2 Froyo smartphones. Still with the Awesome Screen, instant access of recent history, bookmarks and tabs just by tapping in the Awesome Bar will certainly gives you pleasure to browse web. See the release notes for a full list of features included in this release.
With Firefox Sync, easily transfer your browsing history, bookmarks, tabs, passwords and form-fill data with you anywhere so you never have to retype passwords or long URLs again. Your Firefox data is completely encrypted end-to-end between your computers so that only you have access to it. Let’s see the images below Firefox 4 Beta running on Samsung Galaxy S.
Update: Mozilla FireFox Fennec Android Browser Download v4.02b