The port of their windows Geforce driver to linux was reported to have taken a few months. As I understand it, they're still maintained from the same tree and share essentially all code but the minimum necessary glue (much to the annoyance of the linux kernel folks, it should be added).

Tegra is, no doubt, based on the same hardware components they're shipping in their other products; and its driver is surely similarly portable. This isn't a technical point, it's just FUD.