ATi is throwing a hissy fit, and moaning and complaining about, and generally dropping every excuse they can find about why they "need" a closed driver, when in absolute fact they just dont. They have patented hardware. They can protect those patents by using a firmware. Period.
And the most messed up thing about all of this is that if ATi made it modular enough, they could swap out older and slower portions of the firmware with newer optimized versions on the fly during run time if they wanted to. The technology exists, and is readily available today.