RHEL with the Trinity Desktop Environment (TDE)

TDE is the unofficial continuation of the KDE 3 project by a new team or as they put it a desktop environment for Unix-like operating systems with a primary goal of retaining the overall KDE 3.5 computing style,

that took the code when development on it ceased and all resources in the KDE camp moved over to 4. Trinity is more though than KDE 3 in maintenance mode though as they actively progress their own implementations of libcaldav and libcarddav libraries for the PIM-suite (now called Trinity PIM suite) and have taken over maintaining QT 3 with hundreds of patches applied since the last official update.