I have an AMD 6950 and am running windows 8 RTM.
I've tried the Catalyst 12.8 drivers and the 12.9 beta drivers.
With either drive HDCP seems to be non operational.
I've got two dell monitors, one a u2410 and the other a 2408wfp. Both were previously identified as supporting HDCP in windows 7 with the same hardware.
I've tested the monitors individual on both DVI and display port, and neither one works.
I'm using cyberlinks BD-Advisor to test. My end goal is getting the DirecTv2PC app working again, which is by cyberlink for DirecTV, and requires HDCP. Currently it shuts off when you start playing a recording.