Windows 8 has a Messaging app that, despite the same name, is not quite the same thing as the app found on Windows Phone.
Windows Messaging: Say Hello To The Metro Cousin Of The Live Messenger
Youtube user Hoahrgi is showing us the messaging app
The Windows 8 Messaging app is not actually a clone of the Messaging app in Windows phone. Even though this is a Metro app (Metro is adapted from Windows Phone), this app on the Windows 8 OS is more akin to the Windows Live Messenger app that many of us use now. For the uninitiated, Windwos Live Messenger is the Gtalk of Microsoft or the Yahoo! Messenger of the Windows Live ecosystem.
One of the obvious differences between the Windows 8 and Windows Phone apps is that the latter handles SMS and MMS messages and the former of course, does not. Instead, you will get connected to your social messages from Facebook and from Microsoft Messenger network.
Since this is a Metro app, you can easily go in to the fullscreen version. It will look very sparse to those used to the clutter that is desktop apps. But that is the beauty of it. It has a pane on the left for listing recent conversation threads and you can jump across multiple platforms to keep track of conversation. Right now it is only Messenger and Facebook but hopefully others will be added soon.
There’s an app bar within the interface that you can activate for accessing more options. To do this, hit WIN+Z or just swiping up from bottom edge or down from upper edge. There are options for adding new threads, changing your online status, manually switching between services and deleting the currently selected thread. The ‘New’ option lets you start a new thread and it take you to the ‘People Picker’ screen to choose the contact you want to start the conversation with. If you go to this screen through the Messaging app, you will only see those contacts who have compatible services and not every single person your list.
The app still needs work to add advanced features like multi-chat and audio/chat and file sharing. These will probably come with the final version, which we will see in the Release Candidate build.