The NVIDIA Tegra 4 features a GeForce graphics processor with 72 cores, a new computational photography architecture, LTE support, 4K ultra-high-def video support, and is built around a quad-core ARM Cortex-A15 processor. The Tegra 4 was developed under the "Wayne" codename.
The Tegra 4 press release was entitled NVIDIA Introduces World's Fastest Mobile Processor. Other Tegra 4 details are available from the Tegra product page.
I am extremely excited for the NVIDIA Tegra 4 as this is one of the early SoCs using an ARM Cortex-A15. My benchmarks using a dual-core Cortex-A15 in the Samsung Exynos 5 Dual have shown the A15 is crazy fast and can easily beat the Tegra 3 and some x86 hardware. Having a quad-core ARM Cortex-A15 is going to extremely fast in the ARM world and I can't wait to begin benchmarking!
NVIDIA has already been publishing Tegra 4 Linux kernel support code since December. There's new Tegra 4 Linux patches as recently as yesterday. It looks like the Tegra 4 mainline Linux kernel support will come together with the Linux 3.9 and Linux 3.10 kernels.