NVIDIA continue being quick to advance their Vulkan drivers as today they released an update to their special Beta branch.
440.58.01 is out which adds in support for two more Vulkan extensions with VK_KHR_shader_non_semantic_info and VK_EXT_tooling_info which sounds quite useful to help developers track down what might be causing an error.
For games this release fixes up a Vulkan swapchain recreation crash with F1 2017, Rise of the Tomb Raider and DiRT 4. NVIDIA also solved an issue with visual glitching of Vulkan applications when "falling out of flipping" with an example being when you alt+tab, however they're still investigating an issue to do with this on the GNOME desktop.
You can see their special Vulkan Beta page here.
Should I be using this? What's the difference to the normal drivers?
This is the testing area where NVIDIA put in new features, add in new Vulkan API support and more that eventually make their way into their normal drivers. Only use them if you want to test the very latest stuff. You can tell they're the Beta drivers by the extra two digits in the version number. The newest stable version of the NVIDIA drivers for Linux is 440.59 released earlier this month.