ARM is also moving forward with a big.little architecture that duplicates the CPU cores for either high-energy or low-energy situations.
Intel still has a way to go…
Apples to oranges. The Surface RT is an iPad competitor. The Surface Pro is a PC. You can make business arguments as to which is the more appropriate device and which makes the better tradeoffs, but there's no serious technical point to be made here.
Intel has much to fear from ARM, but not from NVidia... especially big.little. Outside of NVidia-specific project Shield, it doesn't sound like Tegra 4 has any design wins. In fact, NVidia's big.little architecture is arguably a failure. Surface RT == NVidia Tegra 3 with big.little (btw: Surface RT doesn't use big.little features at all. Perhaps Microsoft is trying to keep SurfaceRT code portable across different ARM chips). In comparison, the iPad4 is an Apple custom ARM chip, and the Nexus 4 is Qualcomm Snapdragon. Current Nexus 7 is Tegra3, but the next one is rumored to be Qualcomm Snapdragon as well.
Basically, NVidia is weakening in the mobile sector. ARM overall is strong, but big.little is arguably a failure at this point.
Are there any big.LITTLE implementations out there? Wikipedia only mentions Samsung Exynos 5 Octa, which doesn't have any designs right now.