John Carmack made a pair of posts on Slashdot about video hardware as it relates to the engine for their upcoming DOOM III (thanks Jacek Fedoryñski). The first post warns against misinterpreting things he's said or trusting paraphrased quotes that goes on to point out that the ATI 8500 is faster than a GeForce4 on paper, but not in real life, and pointing out the hardware they demonstrated the game on at E3 was not the 8500. The second post offers a bit more, discussing the impact of hardware limitations on game design, and going on to describe the kind of shelf life they expect for the DOOM III engine as well as good news for those hoping for a Linux version. Here's the part that covers those last two points:

Our "full impact" platform from the beginning has been targeted at GF3/Xbox level hardware. Slower hardware can disable features, and faster hardware gets higher frame rates and rendering quality. Even at this target, designers need to be more cognizant of performance than they were with Q3, and we expect some licensee to take an even more aggressive performance stance for games shipping in following years.

Games using the new engine will be on shelves FIVEYEARS (or more) after the initial design decisions were made. We had a couple licensees make two generations of products with the Q3 engine, and we expect that to hold true for DOOM as well. The hardware-only decision for Q3 was controversial at the time, but I feel it clearly turned out to be correct. I am confident the target for DOOM will also be seen as correct once there is a little perspective on it.

Unrelated linux note: yes, there will almost certainly be a linux binary for the game. It will probably only work on the nvidia drivers initially, but I will assist any project attempting to get the necessary driver support on on other cards.