The Next4 and Next 6 both have capacitive touchscreens, Wifi, and accelerometers. The Next4 has a 10" screen (1024x768), 8GB Flash, and runs Android 2.2. The NEXT6 has 7" screen (resolution?) and runs Android 2.1.
Like the Next2, they're tied to the Borders ebookstore. But since they're open tablets you can also install other reading apps. Retail will be $250 (Next6) and $350 (Next4) and they'll be available next quarter (hopefully).
It's been a while since I had it in my hands, but I really think the Next6 is simply an updated Next2. That might be a good thing; the Next2 wasn't all that bad of a tablet. And the Next4 was a monster, but you kinda expect that. I'm hoping the video performance will be better than on the Next2; it would be great to do real 720p on the 10" screen.