Sometimes the smallest additions to an app can offer the biggest gains. Case in point: Facebook, which has just received the ability to send and receive voice messages through its Android and iOS app. This is perfect for those times when you either don't feel like typing out a decently-written message on a small phone, or when you need to discuss something in good detail where text becomes horribly inefficient. In an example shown, reciting off directions is one cool use of the feature.
In order to take advantage of the feature, you need to click the + sign next to the text-entry box, which will reveal the new option. You then tap and hold the record button, speak your message, let go and hit "Done". You can scrap any message you don't want, although it seems you're unable to preview your message prior to sending it. You can however listen to it after it's sent.
Before you get too over-zealous with this feature however, it's important to note that voice uses much more data than simple text, so bear that in mind if you have a ridiculously restrictive data plan. Generally speaking, voice itself requires much less bandwidth than music, but it could still add up over time if you make good use of the feature.
It's also worth nothing that it seems tablet versions of Facebook didn't gain this feature - or at least mine didn't (Android).