See here, News - Steam Client Update Released
I haven't got one to test unfortunately
- Added Steam Configurator support for PS4 Dual Shock Controller. Enable in Big Picture settings Add/Test Controller settings. When enabled, PS4 controllers will have access to the same sort of customization/configuration support as Steam Controllers, including native API support. PS4 Controllers using this system can map the trackpad, gyro, buttons, etc. to keyboard, mouse, or x-input outputs and can make use of action sets, touch menus, radial menus, and so forth.
- Added software gyro+accelerometer integration for IMUs without hardware integration. Allows Joystick-Move/D-Pad/Mouse Leaning support for the PS4 gyro input.