In reply to geologist:
I have read in loads of articles over the years that small doses of protein consumed within 20 minutes of the training session can significantly improve recovery ( there is some rule of thumb on gs protein to kg body mass). The timing is important as your body is very receptive to assimilating the amino acids within a window after the exercise.
I haven't got any of the links to hand so sorry this is vague. I also saw a series on sport supplements once which pretty much concluded that having a pint of milk was as effective as protein supplements (this was following intensive training sessions for rugby layers and cyclists).
Overdoing protein supplements is probably costly, wasteful and probably not too good for your as you have to process all the excess.