Vault 1080, which is a terrible pun by the way, is a free mod of Fallout 4 that is developed by NVIDIA Lightspeed Studios. It is designed to show off GameWorks technologies, such as volumetric lighting and HBAO+, more heavily than Bethesda did with the base game. They claim that the content lasts more than an hour, which is pretty decent for a free expansion.
It will launch on the first day of PAX West: September 2nd.
If you're wondering why NVIDIA has a game development studio, they are mostly responsible for bringing content from the PC to their Shield devices, such as Half-Life 2 and Portal. They also created NVIDIA's VR Funhouse demo, which was also release for free to show off GameWorks (such as NVIDIA Flow and VRWorks Audio) for the HTC Vive. Basically, they develop games (and now game content) to make NVIDIA's hardware more appealing.