No really, they aren't sure. They straight-up asked on Google+:
Here's how you can help. You'll need a Google+ account (resistance is futile). Go here, and +1 the 4th comment.
You have now helped. Good job.
Another important thing to know, the GSM build of the Galaxy Nexus uses a penta-band modem, so, if you can unlock it, it will actually work with AT&T and T-Mobile.