Unplugging might work, but we dont know if it is related or not. What if the same people that unplugged their drive before installing the update were the same people that wouldnt have been affected by the update anyway.
For those that updated and unplugged their drives, can you please post your firmware version and drive version.
On a side note: It still bugs me that people that havent even modded their boxes are getting the same error. I dont know if this is a good thing or bad. I still havent turned on my 360, and I will probably wait until there is more testing done.