An email from the observant (and lemony-fresh) Toilet Duck, points out an interesting quote in the John Carmack interview posted earlier, a reference to 3Dfx's plans to announce a part that supports 32-bit color. Here's how T.D. put it:

In the Mat interview, it's very interesting bit in the second file (about 8 minutes in), where Carmack is talking about 32 bit color. He says that "When they finally announced that they would have this 32 part, Tiwirly was like, 'And this should make John Happy', but I feel that the 3dfx situation is really unfortunate."

The name of the 3dfx guy isn't clear (It sounds like too-early), but you might want to check out the interview at timestamp 8:10.

AFAIK, 3dfx hasn't announced ANY 32 bit parts (external, 3d, etc.), so this would be new, non-public tech.