I've been wondering about that too. Since it's backwards compatible, I assume they didn't "repurpose" any of the lines, although that could be worked around.
Clock increase would be easiest since the clock would be increased freq if 2.0 was detected and remain as-is if not. Encoding scheme would be interesting and today's chipset should support it. Until HDMI 2 is detected stay with current linear encoding and once HDMI 2 is detected go to a lossless compression (for instance). I suspect that might increase handshaking time though.
Either way I'm wondering if any of the cat 6 converters will work. I suspect the answer is no and would be detected as HDMI 1.x anyway. I don't have enough information to guess about Redmere.
Well, I've certainly used up my weekly allowance of speculation with those paragraphs.