From what I've been able to figure out the E7000 adds to the E6500 a dual-core processor, expandable tech slot (maybe more memory in the future, no plans yet and may not ever be used) and better speakers. It is also slightly thinner.
The E8000 adds the Smart Interaction with voice control, gesture control and facial recognition. It also has a built-in camera for Skype, automatic brightness adjust, additional USB port, and better image filter for angled viewing.
All three include internet browser, 2 sets of 3D glasses, and the better real black panel processing.
I was going to buy a E7000 as soon as it was released, but now I'm leaning towards the E6500. I have a surround sound system and HTPC hooked up to it, so I'm not worried about the better speakers or faster apps. I'd rather use the savings on a new subwoofer. Unless anyone knows of another reason I'm missing to get the E7000.