The AES XvBA Reference System is a reference install of Ubuntu for AMD's embedded customers to evaluate the AMD proprietary Linux (Catalyst) driver, evaluate XvBA, and to use this system as a means of investigating and diagnosing bugs in the AMD stack. It's basically the same as installing Ubuntu and then adding in the binary graphics driver, XvBA SDK, and XvBA tools. This modified version of Ubuntu ships with the Catalyst 11.5 driver by default.
Details on this XvBA Reference System can be found from the SourceForge project's read-me file.
While some may find this to be of use and it's nice that AMD is continuing to embrace Linux, XvBA is still too little and too late. It doesn't offer anything over VDPAU and VA-API, which are already the predominant accelerated Linux video APIs.
There is already a VA-API to XvBA library for interfacing VA-API applications with this AMD video interface as well. In fact, it wasn't until recently that the X-Video Bitstream Acceleration API was made public as originally this VA-API front-end was all that could be used.
Phoronix was the first to break the news about XvBA back in 2008 and while it may be able to offload more of the HD video playback work from the CPU to GPU compared to X-Video and XvMC, the initial Catalyst driver implementation was quite buggy. The XvBA support in a modern Catalyst driver is much better now for taking advantage of the UVD2 (Unified Video Decoder 2) engine under Linux, but it's still not as polished and wonderful as NVIDIA's Video Decode and Presentation API for Unix.
Most open-source multimedia application projects now carry support for using VDPAU and VA-API on supported systems. There's also open-source Gallium3D drivers beginning to support a VDPAU state tracker, there is (at least in theory) VDPAU support in the S3 graphics driver blob, and just much more interest throughout the Linux ecosystem for these other video interfaces.
Even Intel's open-source VA-API implementation for the G45, Clarkdale / Arrandale, and Sandy Bridge graphics hardware is better off in many regards than AMD's XvBA under Linux. These days, VA-API works quite well and Intel even recently introduced support not only for video decoding, but also video encoding, using the VA-API library with the new Sandy Bridge hardware. Intel's next-generation Ivy Bridge support should be the same way.