Facebook the biggest social media platform which is the breath of almost 90% of web users launched their Official messenger called FACEBOOK MESSENGER for Windows phones now. It was for just android and apple users and not for windows users. In this act they promoted IM officially after a long time. Facebook all acts are very confuse-able and non-understandable for any person, a world behind geeks just expects good and good from them and by these type of Facebook activities they always made happy its users.
Reason was this windows phone users have very limited advantages as of Android and Apple users because windows launched a couple years ago and didn't supported android app store (The Store from Google Apps) which have almost everything which a tech person needed. Sounds like Epic ! I know, but as far BB officially announced their BBM for androids not for windows, and now Nokia Lumia series are running with windows. Facebook also planning to launch their messenger for Windows 8.1 users that's very recent creation by Microsoft.