http://www.phoronix.com/scan.php?page=article&item=amd_r600_oss_3d
AMD has released open-source code that will form the core of a 3D driver for R600 (Radeon HD3xxx) and R700 (Radeon HD4xxx) graphics cards. Previously, they had released documentation for R500 (Radeon X1xxx) cards that led to a 3D Linux driver radeonhd which is now in Linux distributions as the default driver, but today is the first time an open-source 3D driver has been possible for a current generation of graphics cards.
While this effort was in support of a Linux driver, in theory this code could be used on any OS (for example Windows) to make an open-source driver. This is an important step in Linux becoming mainstream as it means that a computer can ship with all hardware drivers out of the box with no further setup, and also as a philosophical goal in the context of free software.
The code can be found in the xf86-video-radeonhd and other X.Org code repositories, and will enter a release of X.Org (and therefore almost all Linux distributions) soon. The documentation associated with it will be released shortly but is already in the hands of driver developers.
