The necessary patches for implementing BPTC texture compression to turn on the GL_ARB_texture_compress_bptc OpenGL extension were pushed to Mesa Git master. This BPTC texture compression support not only supports the i965 Intel driver with modern HD Graphics (Ivy Bridge and newer) but also the classic "swrast" Mesa software rasterizer.
BTPC is required by the OpenGL 4.2 specification; the extension documentation is on the OpenGL.org registry. The Intel enablement was spread across several commits in Git and will be found in the upcoming Mesa 10.3 release. While the support hasn't yet been mainlined, Nouveau has a BPTC support patch riding off Intel's work and AMD also probably isn't too far behind in adding their support.