The title is not 100% accurate. CUDA has come to mean the tool chain and ecosystem for GPGPU programming. Part of the system is the particular dialect of C++ in which a programmer can mix and match CPU and GPU code. It also includes the compiler that translates the GPU part to object code (the ISA is called PTX [1] which is one level removed from the actual GPU's ISA). What NVIDIA has open-sourced is the part that translates LLVM IR to PTX. The greatest benefit of this will be for people who are developing alternate programming models/DSLs for programming GPUs. They can translate their DSL to LLVM IR, which they probably are already doing, and then generate PTX using the open-source compiler.