Why does every hardware site seem to think Atom or Nano when findig a chip to compare Tegra to?
Truth is the real competitors of Tegra, at least in its first generation, will be the new releases STMicroelectronics STn8820(that have the same specs as Tegra except for the graphics) and OMAP3440 from Texas Instruments(which also seems simular).
Only real thing making the Atom a competitor is the fact that Atom is created to replaces Intels CE 2110 Media Processor, which featured an ARM inspired processor, because Intels saw x86 and compatability with ordinary computers as a bigger advantage than the extra effectivity of ARM processors.