Up to this point the graphics driver for the BCM2835 and its VideoCore processor found in the Raspberry Pi was backed by an open-source kernel driver but a closed-source user-space. Today — through cooperation with Broadcom — the Raspberry Pi Foundation was able to release the user-space bits to to this driver. Therefore there was then a full open-source ARM graphics driver with OpenGL ES 2.0, EGL, OpenMAX IL, etc. The one caveat though was that a firmware blob must be loaded at boot.
It turns out that Broadcom shoved much more into their firmware binary blob than just some basic setup routines and other non-critical tasks. Broadcom’s OpenGL ES (GLES) implementation is even lodged within this GPU driver firmware.
I’m not really sure it’s “open source” when you cram all the good parts into a binary blob. Essentially what they did was make the API slightly more open. I’m a bit disappointed at Broadcom. I’m a big fan of the Raspberry Pi, I own 2 already. However I’d like to see it open enough that it can improve and grow software wise.