The Samsung "ultra def" was shown earlier not really related to the 75" announcement, just cross-linked at Engadget. It's probably something they'll get excited about in 2012-13 for marketing reasons.
"Good news" is that the Samsung 75" is supposedly "only" going to be $13K, so you get just 4 Sharp 70" instead!
Seriously, Samsung plans on selling some quantity of 75s that is approaching zero. I don't really even get why they bother with stuff like that. Sharp, on the other hand, is obviously serious about volume production of their 70-inch line.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.