This takes you to the Messaging screen.
You can use this application to chat with other Windows 8 users who are on chat.
This app seems to be an attempt to compete with other Yahoo Messenger type applications and you will be able to chat straight from Metro.]]>
The chat integrates with Facebook. Whenever someone messages me on facebook, the app sends a push notification along with live tile description.
Good to know..
By the way, looking at your screenshot, I can see you are already connected to Facebook. If you were curious, you could start a facebook chat from the app by right-clicking and clicking new. That will bring up your list of contacts, including facebook friends. Just click on a a contact to start chatting.
I like to use the desktop full screen, then when I get a message notification in the top-right corner, I click it, then snap the Messenger app to the right side of my screen. Then I can continue working on the desktop while reading and replying to messages on the right. I can do this very quickly just by clicking the notification, then pressing Ctrl+. then Ctrl+D. If you prefer the left side, you can press Ctrl+. twice, then press Ctrl+D.