Firefox 4 beta mobile makes use of two new technologies in their architecture. The first one is called Electrolysis and allows the browser to run in a separate process. The second technology is known as Layers and improves overall performance of the browser in graphics areas such as scrolling, zooming and animations.
Firefox 4 Beta also includes Firefox Sync which allows users to sync between their mobile and desktop making their bookmarks, browsing history, tabs, passwords and form fill data available on multiple devices.
Firefox 4 Beta also makes use of the latest technologies such as HTML5 and also supports add-ons. If you have a Android or Maemo based device, you can read more about Firefox 4 Beta mobile or download it from the official Mozilla blog.