iPhone/Android: Facebook pushed out some updates to their mobile apps today, adding Groups to both applications and adding Deals to the iPhone app. The Android app also gets the Places feature, and both phones have a Facebook Connect-like connection with other apps.
When Facebook updated its Groups feature a few weeks ago, you could only access it from your browser, but now those features are available in both the iPhone and Android app — so you can message a predefined group of friends at any given time right from your phone. They've also added the Facebook Places feature to Android, as well as a new Deals feature to the iPhone that helps you find deals from your favourite nearby businesses (US users only, at the moment).
One of the cooler parts of today's update is "single sign on", which is similar to Facebook Connect on the desktop. Now, instead of logging into all your phone's apps separately, the Facebook app will automatically log you in using your Facebook account to apps like Flixter and others. This works on Android or any multitasking-compatible iOS device.
Lastly, the Android apps sucks a little bit less (again). They added the notifications drawer last time, but it directed you to the touch.facebook.com site every time, which was a little ridiculous. Now, if there's an appropriate page to send you within the app, clicking on a notification will send you there. It still doesn't support system-wide notifications for anything beyond the same events, messages and friend requests, but it is one step closer to being on par with the iPhone version.
Facebook is a free download for Android and iOS devices.
Making Mobile More Social [Facebook Blog]