The high-end open-source audio workstation software Ardour is up to version 3.0. Ardour 3.0 features many improvements to this GPLv2+ software.
Ardour 3.0 is the first release of this open-source digital audio workstation software to support MIDI recording, playback, and editing. Ardour 3.0 also improves/changes the audio workflow, which is also very significant.
Some of the other features include parallelization of DSP operations for multi-core processors, matrix-style patching/routing, an overhauled export system, improved audio signal handling, GUI improvements, 64-bit timeline, JACK Session support, dynamically resizable disk buffers, and much more.
More details on Ardour 3.0 can be found with the Ardour.org