KDE developers are now soliciting tests for Plasma Next as the next-generation Plasma Workspace. Plasma Next is built using QML on Qt5 with Qt Quick and an OpenGL scenegraph.
Besides being built on newer software technologies, KDE Plasma Next aims for a converged workspace across form factors, plus other desktop enhancements.
While Plasma Next is just in a testing stage today, the first official release (2014.6) is expected to happen on 17 June. More details via dot.kde.org.