Here's how BlackBerry describes the new BBM service :
BBM Protected offers an enterprise-grade secure instant messaging service with all the features of a consumer IM app, the hardening of on-premise security together with the convenience of a cloud service. All messages are encrypted using keys generated by the communicating mobile devices themselves. This BlackBerry innovation effectively prevents 'man in the middle' hacker attacks, providing greater security than competing encryption schemes, and earning BBM Protected FIPS 140-2 validation by the U.S. Department of Defense.With the announcement this week, organizations using BBM Protected can now let their employees chat securely using BBM Protected to non-BBM Protected workers at other companies, or customers. The result: instant federation and bulletproof security for messaging communications with partners outside of your enterprise.
BBM Protected is available through an extra subscription service via BES, from BlackBerry, but they are also offering a 30-day free trial. The Android version works with Android 4.0 or higher and with BBM 2.6 or higher.
Source: BlackBerry