The Goya brands definitely do as a flavor additive, but there are other brands of Sazon that don't include any glutamate. Then again, Goya has always been the cheap/crap brand of Spanish food.
Badia adds it as well. I'm not just referring to here in the US though. I have a copy of Nitza Villapol's La Cocina Criolla, and almost every recipe calls for MSG.