Rather than add more features and cores in yet another upgrade to the 14 month old Tegra 3 chip, Nvidia instead showed off a new chip with a faster CPU clock speed (1.9GHz vs 1.6GHz) as well as up to 72 GPU cores, not the 12
single GPU core found in the Tegra 3. The Tegra 4 is also using the new Cortex A-15 in those 4 CPU cores, not the Cortex-A9 found in the Tegra 3, and Nvidia is promising that the Cortex-A15 along will offer up to 2.6 times the ability of their earlier chip.
That's cool and all, but the important news today is the 72 GPU cores. That's far more than I could conceive of using myself, but I bt I can sum up Nvidia's design concept in 3 words:
Retina Displays - plural.
While the Tegra 4 is being used to run Project Shield, Nvidia's new 5" gaming handheld, I think the extra cores were inspired by a device with a much larger screen.
When "the new iPad" launched last Spring it had a quad-core GPU chip, and it likely needed the extra processing power to support the 4 times as many pixels found in Retina Display. Nvidia is likely planning on offering the Tegra 4 chip to tablet and smartphone makers so they can offer specs which beat the latest generation iPad. Or at least they hope it will be better than the specs which Apple may or may not announce in the next few months.
In any case, the difference between the top and bottom of the market increased significantly today. And while I'm still not sure that anyone will actually find a need for all that extra power (not unless someone releases a Retina Display equipped TV), it's still good to have the option. It's also fun just to think about the possibilities.
Update: Vizio had a Tegra 4 tablet on display. It couldn't actually do much but Gizmodo still believed it was fast.
P.S. I do actually have a Nexus 7 in the mail; it was an impulse purchase in an after Christmas sale. It's probably going back.