Gear Live has a great short video of the Series 3 prototype in action at CES. It features TiVoPony showing off features (TiVoPony is the TiVo employee that hangs out on the TiVo Community board). The front LED display is incredibly sharp and looks handy. The way the multiple tuners works looks pretty smooth. Pony also covers how hard drive upgrades will be simple plug-n-play type upgrades. The new remote control is also covered, which features a way to tell top from bottom, even in the dark (they have ribs on the back, on one side).
I can't wait to buy one of these boxes and ditch my crappy cable-provider DVR, and if anyone at TiVo is reading this, I will name my next child after you if I can get a unit for early review when they're closer to being done.