This was news to me. It makes me very happy to see this. Long story short, Nvidia and ATI/AMD are providing programming API's to allow software in the *nix world (Linux, BSD, Solaris, etc) to utilize GPUs on their hardware. Specifically,VDPAU from Nvidia and XvBA from ATI/AMD are the systems for the X Windows System. They are equivalent of the Microsoft's DirectX Video Acceleration (DxVA) API for Windows.
Those links will give you more information if you are interested. There are several other programs I personally know of, most notable Avidemux's latest development branches, which are working to make use of this new programming API and technology. It makes me pleased to see these systems coming into place in the *nix world, breaking down yet another barrier between competing Operating Systems.
Even though the protocols from Nvidia and ATI are still limited in what they can do, I have little doubt the capabilities will be extended and based on stirrings in the Windows world, I am sure of it.