http://www.raspberrypi.org/archives/6299

Broadcom announced the release of full documentation for the
VideoCore IV graphics core, and a complete source release of
the graphics stack under a 3-clause BSD license. The source
release targets the BCM21553 cellphone chip, but it should be
reasonably straightforward to port this to the BCM2835,
allowing access to the graphics core without using the blob.

Reg level doc & sources @ http://www.broadcom.com/support/