Wife is going to tough out this issue until the SGS3 releases on VZ, and we are trading it in then. I will keep mine as I do not use the phone enough to have gotten this problem (though I know my phone has it, as I swapped with the wife already to test). I don't think it is a phone issue, but a VZ issue with certain locations/towers.
Minneapolis here. Not exactly the mega population center of the Midwest, but when you track this issue by location... it pops up way more than it should. Carolinas and CA too.
For those of you that are keeping the phone anyway, and heck for everyone else out there that feels for those of us that WANT a Nexus phone... go to this link and STAR the issue for us.
Issue 24019 - android - Galaxy Nexus mutes mid-call - Android - An Open Handset Alliance Project - Google Project Hosting
I do have some concerns that the SGS3 will use the same baseband chipset, and that that theory of what is causing the problem is correct. If it is, the SGS3 might have the same problem. Supposedly the Samsung Droid Charge does as well. But at least we will then be on VZ purchased phones, and can swap until they let us choose another if so.