For several months now there's been Radeon KMS porting of the open-source Linux code to FreeBSD. Good progress has been made although there's still an assortment of bugs and other improvements to be had, after the first Linux KMS driver was merged for FreeBSD 9.1: open-source Intel graphics support.
It's been looking like the Radeon KMS driver would be in shape to premiere in FreeBSD 10.0 and we now know for sure that it will. An update posted last week to the FreeBSD Wiki states, "good news: the driver will be committed to HEAD in the short term so that it'll be part of 10.0-RELEASE!"
The FreeBSD AMD Radeon driver is based upon the Linux 3.8 kernel code while much of the user-space Mesa/Gallium3D code changes have been merged into Mesa 9.2. This is really good news considering that AMD currently provides no BSD support with their Catalyst driver. This open-source driver porting also isn't being done by AMD employees but rather independent FreeBSD contributors with funds from the FreeBSD Foundation.
This Radeon FreeBSD news also comes just days after Radeon KMS support was committed to OpenBSD.