Plasma Mobile is the newest member to the family of Linux-based operating systems. The OS was announces during a KDE event called Akademy. The KDE community released a prototype of the OS running on Google's Nexus 5 device.
It runs on Kubuntu and uses the much talked about Wayland display services.
Unlike other operating systems, Plasma is trying to be more inclusive and can run apps written for Ubuntu phones as well as Android.
Looking at the reputation of the KDE community to stick to open standards, this could be, along with Firefox OS, the most 'open' mobile operating system.