The Floobits Package for Atom is now in Beta. It adds support for real time collaborative editing for multiple files and users (across text editors). It also adds support for shared terminals via the Term3 Package and video chatting via WebRTC. A Floobits account is required, but the plugin will help you create one or login.
The docs are on floobits.com.
We had to solve quite a few time consuming problems along the way including supporting github OAuth (communicating between a webview/iframe and the plugin), making React work, and message passing between Atom windows. The source is on github if you are interested. I’m also happy to answer any questions you may have.