To explore NVIDIA's booth here at Mobile World Congress is to play a game of duck-duck-goose. For the most part, you'll see the Transformer Prime (the first quad-core tablet, don'tcha know) outputting video and 3D games. But look closely and you'll find something a little less expected. Hidden among all those spun metal Primes is an unannounced Toshiba-made tablet, one with an odd, in-between screen size we haven't seen
