Well this is interesting... I'm the OP and I must have mentioned this to service a few weeks ago, as when I called in today about another issue, they brought it up with me as having reported it.
In any case, Eric at the Rockville Service Center told me that it's an issue on Google's side (they do the processing, as we had surmised), but only affecting our area (DC/MD/VA) for some reason related to security. The expect a permanent fix soon.
Here's the cool part: in the mean time they can send a work-around patch to affected VINs over the air. The caveat is that it won't hold past either a scroll-wheel console reboot, or firmware update. But if that happens you can call and ask them to reapply the patch.
One additional reason why this car-as-a-platform is uber kewl. And why bringing your service folks donuts pays off.