Mozilla has officially released its Android incarnation of Firefox 4. And for those of you who still care about such things, the open source outfit has also released a version for Maemo.

The Androidian browser is available from Google's Android Market, while the Maemo version can be downloaded from Mozilla.

Firefox 4 for mobile includes Mozilla's Firefox Sync service, which lets you synchronize browser data across multiple devices. Originally known as Firefox Weave, the service syncs bookmarks, history, "Awesome Bar" data, passwords, form-fill data, and open tabs. Mobile Firefox can also accomodate those famous Firefox add-ons, and it offers a new phone-centric interface that hides the browser controls when you're not using them.

The original Firefox 4 beta had an obesity problem. It required about 40MB of storage space. But we've download the latest version, and it takes up little more than 17MB.

Whereas WebKit browsers can use the rendering libraries bundled with Android, Mozilla must include Firefox's libraries in its APK (Android package) file, and due to the way Android is designed, the libraries ended up in two different places. They were compressed in the APK, and they were extracted to a folder when the browser is installed. With the original beta, Mozilla hadn't yet found a way around this, but it's now using a dynamic linker that can load the rendering libraries from the APK without copying the libraries to a folder.

Opera must deal with the same problem.

Mozilla claims that the browse is about three times faster than Android's native WebKit-based browser. Firefox 4 for mobile offers Mozilla's new JagerMonkey extension to its JavaScript engine. JagerMonkey operates alongside the existing TraceMonkey extension. TraceMonkey speeds JavaScript performance by detecting code loops and converting them to assembly language, and when this isn't an option, JaegerMonkey converts entire methods into assembly.

There are also tools for instantly sharing URLs via services such as Facebook, Twitter, and Google Reader and for saving pages to PDF format for offline viewing. ®