This is big news. Apparently, AMD is promised to publish specs for cards >=R500 which is great news. I've been a fan of ATI for a long time, and I've even become a bit of an expert when it comes to the fglrx driver. I don't have any problem getting hardware acceleration to work on any of my boxes, but I've had to fight with it on SuSe and RedHat.
While I suspect that Dell had something to do with this, with their fancy shmancy Ubuntu Linux line of desktop computers, this is great news. If I thought for one second that the radeon driver would compare with fglrx driver (which it honestly doesn't), then I would have taken the free driver over the proprietary one. However, I'm not gonna cut off my nose despite my face in the name of "Free as in freedom" I'm a GPL kinda guy, but there's a limit to my fanaticism.
I am excited about this. However, a point was brought up on an IRC channel I frequent that while the GPU specs may be published, there are other decoders on the card for HDMI, DVI, and other encryption and DRM enforcements that most likely will not be published. Why? ATI is probably under a pretty strict NDA from their vendors. Although I'm not super familiar with HDCP, it also has engineering requirements which restrict the firmware on those cards, and can't be controlled via software, so no go for HDCP with any new drivers. Of course, I'm sure you'll be able to find something similar to the non-free repositories that we all go to for libdvdcss2 (which is illegal in the U.S. - come and get me...)
This is great news for the linux community though.