Whey is broken down into its constituent amino acids and assimilated into the bloodstream very rapidly, hence why it is the protein source of choice after a workout. This isn't desireable at most times of the day, however. Including fat in the same meal will slow gastric emptying, and subsequently help streamline the release of amino acids into the blood.
so say I'm at work and I need a quick protein fix....I drink a whey shake and a spoonful of PB and I'm good to go? Sweet....