Mixer is a Blender addon developed at Ubisoft Animation Studio for Real Time Collaboration in 3D edition. It allows multiple Blender users to work on the same scene at the same time. Thanks to a broadcasting server that is independent from Blender, it is also possible to implement a connection for other 3D editing softwares.
This looks interesting in concept. I am particularly intrigued by the "it is also possible to implement a connection for other 3D editing softwares" line. I'm not sure if that means between the same software that are not blender or between blender and another software.