Steam now boasts official support for the DualShock 4, ie, Sony's much-loved PS4 controller. Valve announced the support was incoming at Steam Dev Days last month, but now you can go and use it right now – though it's still in beta.
According to the most recent Steam Client Beta Update, which rolled earlier today, the DualShock 4 will now boast "the same sort of customization/configuration support as Steam Controllers, including native API support". To activate DualShock 4 support now, you'll need to enable it in Big Picture settings, under the Add/Test Controller tab.
Here are the full patch notes pertaining to the DualShock 4, for your convenience:
Added Steam Configurator support for PS4 Dual Shock Controller. Note that this is a beta release. 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 New Mode – Joystick Mouse. This is a joystick based mouse control useful for stick based controllers.
Added default PS4 templates.
Added software calibration for non-Steam controller based IMUs to counter for gyro drift.
Configuration Browser can now be toggled to show all available controller types rather than the default of the in-use controller type.
Configurations can now be marked as “Unique” to a specific controller. This configuration will only be applied to that controller for that user’s account. By default, all controllers of a specific type will share a configuration unless marked as Unique.
Big Picture now supports PS4 controller glyphs when using Steam Configurator support.
Despite not having official Steam support for years, the DualShock 4 has long been one of the PC Gamer team's favourite controllers, as its placement in this list will attest.