I hate being a spoilsport, but it is actually illegal to possess the Doom 3 alpha. Despite what some people seem to think about leaked pre-releases, being the property of the developers/publishers/etc means that unless they release it in whatever manner they dictate, then it's an illegal release. In this case, an ATI employee leaked it, and despite what anyone may think, it IS warez. Activision and id Software have forced many sites to take down their screenshots as a result.
Despite leaking this release, ATI will still be working with id in graphics matters. The relationship has been soured, especially given ATI's history of leaking information, but they will continue to work together to optimise video drivers and game performance. I wouldn't go so far as to say it's "optimised" for Radeons, but the Radeons are capable of rendering more textures per pass than any other cards. Which is one of the reasons Carmack will continue to work with them.
Slightly off topic, the NV30 has been delayed again. Expect to see them in Q1 next year. In the meantime, nVidia are bringing in "enhanced" versions of their current cards to fill the gap, but they are still falling short of ATI's current offerings.
Still looks nice (what's in the screenshots) for less than 5 minutes of gameplay. I'll be interested in seeing the finished product, when I have the CPU power to drive it.