I just found on [H]ard|OCP forums the MSI Kombustor 1.1.3 score of a Radeon HD 6870 (with Catalyst 10.10). The settings are 1920×1080 fullscreen, 60 seconds and unlock power draw UNCHECKED (default mode), no AA and no postfx.
I quickly ran a the same test with my GTX 460:
Radeon HD 6870 is Twice Faster than GeForce GTX 460 in MSI Kombustor - 3D Tech News, Pixel Hacking, Data Visualization and 3D Programming - Geeks3D.com