Facebook is moving all chat features out of the main client and into the Messenger app. Many mobile users will now need to use this app for their IM needs, though some platforms won't change.
HTC One M8 for Windows Review: Making a run for the top
Nokia Lumia 530: A first look at Microsoft's new low-cost Windows Phone
A version of Facebook's rumoured Snapchat-rivaling photo messaging app, Slingshot, appeared erroneously on the App Store for a few hours earlier today allowing some to download and try it.
The social network Facebook is rumoured to be building its own rival to the popular Snapchat photo and video-messaging service after an unsuccessful attempt to purchase the company last year.
The popular IM program WhatsApp has been removed from the Windows Phone Store without explanation - but the good news is that the app is still working for those with it already installed.