With most of the lifting out of the way by Intel's work, Ilia added support to Gallium3D for the BPTC formats, added the support to the Mesa state tracker and expose the GL_ARB_texture_compression_bptc, and then implemented the work within the NVC0 driver. The ARB_texture_compression_bptc texture compression support is mandated by the OpenGL 4.2 specification.
The four patches implementing the BPTC texture compression support can be found for now on Mesa-dev while they'll likely be committed to Mesa Git soon enough ahead of the 10.3 release. It probably won't be long now until Radeon Gallium3D also takes advantage of this texture compression extension.
Update: There's also now a patch to support BPTC for the Radeon R600g driver that rides off the Intel and Nouveau patches.