First of all, KDevelop 4.6.0 improves debugging support with GDB. The GDB integration improvements include some operations now going into effect immediately rather than needing to re-run the program, debugging from external terminals is now better, and there's a CPU registers toolview. KDevelopers' CPU registers toolview also allows for showing and editing all user-mode registers and general purpose flags for x86/x86_64/ARMv7 platforms.
Other KDevelop 4.6.0 changes include greater language support within the PHP plug-in, Python language support improvements, more C++11 language support, improved project management, and a clean-up to the IDE's user-interface.
More details on the fresh release of KDevelop 4.6.0 can be found from the KDevelop.org announcement.