Facebook Messenger app, an extension of Facebook messages for member-to-member messaging, texts, and picture or location exchanges, has been upgraded with new features. Now you can see who’s online and who’s on mobile, and know when the other person is typing. It’s also easier to send messages to the people you message most.

The app is now available for BlackBerry in addition to iPhone (including iOS 5) and Android. Facebook Messenger now shows application users on iPhone, Android and BlackBerry which of their friends are online or available via mobile.

Messages are delivered through notifications and texts, so your friends are more likely to get them right away.