Did some googling. Most likely causes are water-pump, alternator or just a bad belt.
Since we aren't in a huge rush, I'll take it home, pull the serpentine belt off and see if the car still whines. Then turn the alternator by hand to see if it whines, I have a feeling this is the culprit for some reason. And debug from there. If it's the water pump I'll bring it to Toyota for warranty work, if it's a bad belt or alternator I'll just swap it out. This is just more annoying than anything....