Took my BRZ to the dealership today to get them to order a new taillight for me.
They referred me to TSB 07-59-07 (12/17/2007) and sent me on my way *without* ordering a replacement taillight.
They said it's normal for condensation to form in the taillights & headlights. The only way they would order a new unit is when there's standing water within the housing.
That was a waste of an hour's drive. Damn.