How many active BBM users exist worldwide?

According to Research In Motion (Ticker: RIMM), the makers of the Blackberry and Blackberry Messenger app (BBM), there are well over 50,000,000 active users of the app, and they claim that more than 2,000,000 new users join the BBM community every month.

BBM has a platform of APIs for developers to use to create apps that take advantage of BBM being "always-on, and always instant," having tools to share location data, and even the opportunity to use the built-in camera for real time streaming of video.

In mid July of this year Research in Motion introduced 2 new Blackberry devices: the Curve 9320, and the Curve 9220; both offer updated social media capabilities as well as better battery life.