I can confirm that this works:
IF YOU UPGRADED TO 8.0.1 AND CELL SERVICE IS BROKEN:
Go to ipswdownloader.com and download the iOS IPSW for 8.0 for your respective model.
Go to iTunes and Option-Click "Check for Update" Select the downloaded 8.0 IPSW and update the phone. It will revert back to 8.0 and cell + touchID will work. You will not need to backup & redownload all your stuff - it works like a normal upgrade.
I can also confirm this works. I'm back up and running on 8.0, no data loss. It's as if I never updated to 8.0.1.
For Windows users that is 'shift-click "Check for Update"', btw.