Due to the rather open process WhatsApp use to generate their localization resource files we often get an early view of coming features.
The latest to be revealed by such a translator is the imminent arrival of individual chat backgrounds, of course already a feature on other platforms.
The feature is a nice indication of WhatsApp working actively to get their Windows Phone app on parity with their clients on iOS, something I wish other cross-platform developers would emulate.
For an idea of what it would look like, here is an example for Android, from a page listing 10 features WhatsApp is missing on Windows Phone present on other platforms.
Thankfully it looks like most of those boxes have now already been ticked.
Via Mobiflip.de, thanks Frank for the tip.