AFAIK they're the old same FireGL 8700/8800 drivers I believed in a lot when I learned about them... Turns out they didn't work very well (not at all for me), and it's a royal pain to make them work on non-built-by ATI cards.
Wether they indeed support R300 remains to be demonstrated...
Proud owner of a Hercules Radeon 9800 Pro
Intel P!!!-S Tualatin 1266MHz | ASUS TUSL2-C i815EP | 512MB PC-133 | Antec True Power 380W
MSI GeForce 4 Ti4200 @ 250/515 | Creative SoundBlaster Live! | D-Link DFE-528TX 10/100
2 x Seagate Baraccuda IV 60GB ATA-100 7200 RPM HDDs | Pioneer DVD-117 16x/40x DVD-ROM
Windows 2000 Server SP2
DirectX 8.1 (4.08.01.0881) - nVidia Detonator 43.45 - 3DMark2001 : 8433
DirectX 8.1 (4.08.01.0881) - nVidia Detonator 30.82 (WHQL) - 3DMark2001 :
Slackware Linux 8.1
nVidia Linux IA32 Driver 1.0-4191