1. At a computer system including one or more processors and system memory, the computer system also including a physical graphics processing unit (“GPU”), a method for providing a programmable GPU pipeline to a guest application executing in a child partition of a para-virtualized execution environment, the method comprising: an act of instantiating a virtual machine session, including instantiating a hypervisor that provides (i) a root partition having access to the physical GPU, and (ii) the child partition which executes the guest application; an act of presenting a virtualized graphics processing unit (“vGPU”) to the guest application, the vGPU executing within the child partition, the vGPU including: a first user-mode driver (“UMD”), executing in a user mode of the child partition, that presents a first plurality of device driver interfaces (“DDIs”) of a first version of a rendering framework to the guest application, the first plurality of DDIs enabling the guest application to send commands to the vGPU for programming a GPU pipeline of the physical GPU to utilize one or more features unique to the first version of the rendering framework, including utilizing at least one of: a domain shader, a hull shader, or a geometric shader; a second UMD, executing in the user mode of the child partition, that presents a second plurality of DDIs of a different version of the rendering framework to the guest application, the second plurality of DDIs enabling the guest application to send commands to the vGPU for programming a GPU pipeline of the physical GPU to utilize one or more features unique to the different version of the rendering framework; a first kernel-mode driver (“KMD”) processing component that corresponds to the first UMD, that executes in a kernel mode of the child partition, and that receives a first command buffer from the first UMD and constructs a corresponding first direct memory access (DMA) buffer; and a second KMD processing component that corresponds to the second UMD, that executes in the kernel mode of the child partition, and that receives a second command buffer from the second UMD and constructs a corresponding second DMA buffer; an act of a first render component executing within the root partition receiving the first DMA buffer from the first KMD processing component, the first DMA buffer including at least one first physical GPU-specific command for using a feature unique to the first version of the rendering framework including one or more of a domain shader, a hull shader, or a geometric shader at the physical GPU; an act of a second render component executing within the root partition receiving the second DMA buffer from the second KMD processing component, the second DMA buffer including at least one second physical GPU-specific command for using a feature unique to the different version of the rendering framework; and an act of the first render component and the second render component scheduling the at least one first physical GPU-specific command and the at least one second physical GPU-specific command for execution at the physical GPU.