Kali Linux has been released yesterday, 11-Aug-2015. Kali Linux 2.0 is now with a major release in tools, distribution and user interface since March 2013. Here are the major changes that you can see in Kali Linux 2.0.
new 4.0 kernel
based on Debian Jessie
improved hardware and wireless drivers
support for variety of Desktop Environments (GNOME, KDE, xfce, mate, e17, lxde, i3wm)