Microsoft's Facebook Beta app, essentially the development version of the official Facebook app for Windows Phone, is now available for Windows Phone 7.8 devices (version 3.1). The app, which is also available for Windows Phone 8 devices (version 5.1), offers an improved Facebook experience over the standard Facebook app.
Microsoft has announced a beta program for the Windows Phone 8 Facebook app, which it says will help "speed up delivery of new features in the official Facebook app for Windows Phone", and is looking for "sharp-eyed, energetic volunteers to download a beta version of our next release and tell us how to make it better". The first beta version, which is being made available along the current release version, offers a major redesign and includes several new features.
The new design is more closely aligned with the look of the Facebook app on other platforms (iOS and Android). For example, the large header text is replaced with the standard Facebook shortcuts (Menu, Friends, Messaging, Notifications Chat). Swiping to the right exposes a navigation list giving quick access to various sections and functionality, whilst swiping to the left shows a list of chat contacts. In general the new design feels cleaners and has less clutter, though some may mourn the loss of the direct "Metro" design pattern.
Since the intial beta release on Windows Phone, Facebook Beta has received a large number of updates, which have added new functionality (inline tagging, photo attachments in messaging, emoticons in status updates, the ability to unfriend people, and more) and optimised overall performance.
The Windows Phone 8 and Windows Phone 7.8 versions if the Fcebook Beta app, despite their differing version numbers, appear to have the same design and feature set.
Windows Phone Store description:
Facebook for Windows Phone makes it easy to stay connected and share information with friends. Thanks for being a part of our beta and helping make Facebook even better on Windows Phone. Along with all the great new features, there could be some bugs. Help us build a better app by sending feedback via Settings > Feedback in the app.
This update includes performance improvements and bug fixes. Facebook Beta is also available for Windows Phone 7 users now.
Facebook Beta is a free download from the Windows Phone Store. To download this app you will need to follow a direct link, it is not visible in a standard Windows Phone Store search (or you scan the QR code on this page).
Microsoft's intention is that the Facebook Beta app will eventually replace the standard Facebook app.