Mageia 4 Beta 1 features installation improvements, RPM 4.11.0 is now the package manager version, Mageia tools have been ported to using PolicyKit, improved hardware detection, there's now the Linux 3.12.0 kernel, systemd is at version 208, and the network interface naming scheme has been changed.
On the desktop side Mageia 4 Beta 1 has KDE 4.11.2 and GNOME 3.10.2 along with the lighter options like Xfce and LXDE. Cinnamon and Mate are also making their premiere in the Mageia world.
More details on this Mageia 4 development update can be found via the Mageia Blog and its release notes.
The official release of Mageia 4 is expected in February.