FreeBSD systems have the same open-source support for Radeon hardware as Linux, including 2D and 3D acceleration for Radeon R100, R200, and R300-series chipsets. The R300 support, as with Linux, remained experimental due to being reverse-engineered from ATI's proprietary drivers, but with the release of official documentation by AMD (following its buyout of ATI), all Radeon families up to R700 have at least 2D support in the FOSS drivers, with basic video acceleration and power management, and up to R500, have at least 'basic' (up to OpenGL 1.5 feature set, GLSL is still a work in progress) 3D acceleration. On R600/700, 3D is still very much experimental, and Evergreen support has barely started due to lack of documentation.
ATI does not support its proprietary fglrx driver on FreeBSD, it has been partly ported by a third party as of January 2007. This is in contrast to its main rival, NVIDIA, which has periodically released its proprietary driver for FreeBSD since November 2002 (64-bit beta driver available as of December 3, 2009). In the meantime, the release is similar to Linux.