Beyond3D has a short interview with John Carmack on Doom III and today's videocards.
If you're using a GF3/4 or Radeon 8500 you'll like this.
You said there are two passes on GeForce 3/4 and one on Radeon 8500. Are
these number of passes *per light*? Say we take 30fps as basis - GeForce3 or
4 could handle about 3 or 4 per pixel lights per frame which actually means
8-10 passes! Radeon 8500 would take 5-6 passes which saves some T&L work.
Yes, the primitive code path is a surface+light "interaction".
We guestimate 2x lights per surface average and 2x true overdraw, for 4x interaction
overdraw (times 5,3,2,or 1 passes, depending on the card and features enabled).