Microsoft engineered Windows Phone to be social and communicative from the get go, with Windows Phone 8 they have pushed that concept even further. Aside from Rooms, Emails, Text Messages and Social networks there are other ways to chat with your friends. One of those ways it to use the free IM app called WhatsApp, a messaging platform that has gained fairly widespread adoption.
We reported a few days ago on an imminent update and good news is that they have just pushed out version 2.8.10 onto the Windows Phone Store. This will update existing Windows Phone 7.x devices whilst also bringing Windows Phone 8 compatibility to the table.