According to a Facebook post by a Nokia employee, an official Windows Phone port of Instagram is in the making. The post got deleted very quickly, so it’s either legit, or contained misinformation. The context is an user asking if the Lumia 920 will receive an Instagram app.
While having apps for Android and iOS, Instagram is notably missing from the Windows Phone store. Nokia recognise that this is a somewhat major sales obstruction and ran a Twitter campaign that practically wooed Systrom and co. to bring their photo sharing app to WP8.Source: WPCentral