I thought we already knew this, since it was included in all those other details that were confirmed shortly after, but everybody else seems surprised so we should probably at least act like we didn’t know (we’re very polite here at CG). Yes, the ZuneHD does officially use Nvidia’s Tegra chipset — its hardware decoder and low power draw made it a natural choice.
I still would have liked to see a slightly bigger screen, the better to show off that beautiful UI, but I guess you can’t have everyzing.