Can't say for sure about the AT&T version, but the Tegra version has it, and it works fine.
I believe this receiver is built into the wifi chip set, which is supposed to be the same on all models of the HOX (its an
Atheros WNC3660)
It might be they left the software off the phone on the AT&T model.
There are Three .apks on my phone that seem to be involved:
FM Radio
FM Radio Widget
FMRadioService
With ES File Explorer, you can often see apps installed but left out of the app drawer or the the app listing in /settings.