To put the record straight: Feige, Goldwasser, Lovász, Safra and Szegedy made the connection between the interactive proof literature and approximation. Arora and Safra showed the importance of reducing random coins and queries and proved a weaker version of the PCP theorem. The theorem in the above form was proved by Arora, Lund, Motwani, Sudan and Szegedy.
I have been teaching off the notes of Madhu Sudan from a short course he taught on the PCP theorem. The notes don't go through every detail, but they give one of the better expositions of what is still quite a complex proof.