First there was the rollout to Android and iOS, and now Windows Phone will be the next major mobile platform to get BBM; BBM for WP is compatible with both Windows Phone 8 and Windows Phone 8.1.
Given that the app is currently in private beta, only those who were lucky enough to receive a beta testing invitation will have the invite code required for the app to function. Windows Phone Central has confirmed that this is the official BBM for WP.
Needless to say this is great news for BlackBerry for several reasons; the introduction of WP support could potentially add several million new users, creating further goodwill for the brand and increased revenue via current and future monetization plans, not to mention making BBM a truer cross platform offering.
This is also a strong statement for the positive changes at BlackBerry under the Chen leadership, more specifically delivering on schedule; exciting times are definitely ahead.