Modern Video Cards with Open Specs?

JessLeah asks: "I've been having trouble finding decent, 3D-accelerated drivers for video cards (of late-90s/early-2000s vintage) under Linux. I'd just get a newer card, but it seems like the situation for newer cards is even worse. The market at present seems to be little more than an nVidia/ATI duopoly, and neither nVidia nor ATI have open specifications available for their chipsets. As a result, both of them presently have binary-only, x86-only, Linux-only XFree86 drivers as their sole alternative to Windows. Are there any modern chipsets (with a reasonable cost) that actually have open specifications available online -- or, at a minimum, open-source drivers that can actually compile on things other than Linux/x86" What was the last video card with open specifications that you can remember?