There's an early test build of Facebook 4.0 floating around out there, which Android Police got their hands on and checked it out. Oh and it's available to download as well. The test build features a new redesign that's a pretty huge redesign. We've already seen some big changes in the Facebook Messenger app, which looks a lot like this redesign you see above. You can tell that the app is now flat, and almost has a look of Microsoft's Metro UI and Google's Holo UI mixed together. Which I'm a fan of both, so I quite like this, even though I don't use Facebook.
As expected with a new redesign, Facebook has moved some things around. At the top, there's the navigation bar and the first one is the news Feed along with some others. Facebook seems to have also moved the Hamburger menu over to the right side, instead of it being on the left. Additionally, they've also moved the status, photo and check in options to the bottom of the page. Which is in line with a lot of other apps out there including Twitter (before they scraped their beta version) and Google+.
Thanks to the folks over at Android Police, we do have a download for the apk. So everyone else can get their hands on the new test build as well. It doesn't seem to be the beta version...yet. But I'm sure it'll be fed to the beta testers really soon. You may need to uninstall your current Facebook app to install this one, which if it's pre-installed on your device, you may need to freeze it. but it's still very easy to install. The filename is com.facebook.katana-188.8.131.52.2.apk
Download: Facebook 184.108.40.206.2