Many multi-monitor improvements are apparent in Windows Blue, and we've created a quick video demonstrating its usefulness! Windows Blue allows those who are using more than 1 monitor to have 2 or more apps open over 2 or more screens at the same time. This means you can have the Mail and People app open on both screens at once, or the Start Screen and Desktop!
Of course, as this is a pre-release build of Windows Blue, bugs are apparent. Just ignore them, we're certain they'll get fixed before the RTM version of Windows Blue. In the meantime, get excited, as we expect many more cool features to be part of Windows Blue!
Currently in Windows 8, it is not possible to have the Start Screen or any Metro app opened on one monitor while the desktop is in use on another monitor. The Metro app or Start Screen will disappear. In other words, the Metro app will not remain in full screen on the second monitor. This feature is apparently being worked on in Windows Blue and it partially works as of the leaked build from today.
The video was made with a Virtual Machine, which means both monitors aren't really monitors (mind boggling!). Check out the video below!