I found an interesting mention of Tegra T114 SoC on a Linux Kernel site, which I've never heard of. I got really interested when it stated that the SoC is based on ARM A15 MP, it must be Tegra 4. I checked the background of the person who posted the kernel patch, he is a senior Nvidia Kernel engineer based in Finland.
"This patchset adds initial support for the NVIDIA's new Tegra 114
SoC (T114) based on the ARM Cortex-A15 MP. It has the minimal support
to allow the kernel to boot up into shell console. This can be used as
a basis for adding other device drivers for this SoC. Currently there
are 2 evaluation boards available, "Dalmore" and "Pluto"."
On the off chance I decided to search www.glbenchmark.com for the 2 board names, Dalmore (a tasty whisky!) and Pluto (Planet, Greek God and cartoon dog!) Pluto returned nothing, but Dalmore returned a device called 'Dalmore Dalmore' that was posted on 3rd January 2013. However the OP had already deleted them, but thanks to Google Cache I found the results
GL_VENDOR NVIDIA Corporation
GL_VERSION OpenGL ES 2.0 17.01235
GL_RENDERER NVIDIA Tegra
From System spec, It runs Android 4.2.1, a Min frequency of 51 MHz and Max of 1836 Mhz
GLBenchmark 2.5 Egypt HD C24Z16 - Offscreen (1080p) : 32.6 fps
GLBenchmark 2.5 Egypt HD C24Z16 - Offscreen (1080p): 49.6 fps
Anandtech has posted that Tegra 4 doesn't use unified shaders, so it's not based on Kepler. I reckon that if Nvidia had a brand new GPU they would have shouted about it at CES, the results I've found indicate that Tegra 4 is between 1 to 3 times faster than Tegra 3.
BUT, this is not 100% guaranteed to be a Tegra 4 system, but the evidence is strong that it is a T4 development board. If this is correct, we have to figure that it is running beta drivers, Nexus 10 is ~ 10% faster than the Arndale dev board with the same Exynos 5250 SoC. Even if Tegra 4 gets better drivers, it seems like the SGX 544 MP4 in the A6X is still the faster GPU, with Tegra 4 and Mali T604 being an almost equal 2nd. Nvidia has said that T4 is faster than A6X, but the devil is in the detail, in CPU benchmarks I can see that being true, but not for graphics.
UPDATE - Just to add to the feeling that that this legit, the GLBenchmark - System section lists the "android.os.Build.USER" as buildbrain. Buildbrain according to a Nvidia job posting is "Buildbrain is a mission-critical, multi-tier distributed computing system that performs mobile builds and automated tests each day, enabling NVIDIA's high performance development teams across the globe to develop and deliver NVIDIA's mobile product line"
I posted the webcache links to GLBenchmark pages below, if they disappear from cache, I've saved a copy of the webpages, which I can upload, Enjoy
GL BENCHMARK - High Level
GL BENCHMARK - Low Level
GL BENCHMARK - GL CONFIG
GL BENCHMARK - EGL CONFIG
GL BENCHMARK - SYSTEM