A video shown on-stage during NVIDIA’s press conference just unveiled “Project Shield,” a gaming controller / portable console running the just announced Tegra 4. The controller looks an awful lot like a PlayStation 3 DualShock 3, albeit with an HD screen attached. NVIDIA’s promising 38 hours of gaming out of the rechargeable lithium ion batteries built-in, a swanky audio system “on par with” jamboxes, and a full-on Android gaming experience. A m…