I'm another one who is experiencing the HDCP problem. I'm using a 3' HDMI cable from my H67 + Core i7 HTPC to a Pioneer SC-05 receiver, and then a 6' HDMI cable from the receiver to the TV.
My 3 Gbps SATA ports started flaking out after 5.5 months, so while that motherboard was sent off for warranty replacement, I put together a temporary HTPC with some old parts including an ATI 5770 graphics card. With the exact same HDMI cables going to the exact same ports on my receiver and TV, the HDCP connection with the 5770 graphics was fine.
I did a few other tests with the integrated graphics, but unfortunately I don't have a very long HDMI cable. I tried a couple of different 3' and 6' HDMI cables, both with the motherboard's HDMI output and with the DVI output + a DVI-to-HDMI adapter. I think the only one that worked for me was using the DVI output + DVI-to-HDMI + 6' HDMI cable, but without audio, I didn't want to go down that route. That gives me some hope that with a long HDMI cable, it will probably be OK, but for now, I'm using the other workaround.
BTW, I'm happy to be back on the Intel integrated graphics. There are some annoying quirks in trying to use an ATI card for a HTPC.