The standard thought is to take protein AFTER workouts (the idea of a post-workout protein shake). The idea here is that during strength training the muscle fibers are ripped a little. After strength training (over the next couple days) you experience that delayed muscle soreness which is your muscles rebuilding to be stronger. Muscles are mostly protein so the thought is to take protein after working out so that your body has the protein that is needed to rebuild.

The thing is that since it takes a couple days for your muscles to rebuild (so the idea that you shouldn't train the same major muscle groups to failure two days in a row) it really isn't as crucial for you to get in additional protein in the hour or two after training that people (particularly bodybuilders) seem to think. It is more important to eat a balanced diet (with the proper ratios of good fats / oils, complex carbs, and protein) EACH and EVERY meal. And... To have 5-6 meals a day (with the total calories being what your daily intake should be given your aims).

But... Most people aren't as serious about it as all that (eating 'proper' takes considerable planning, time, energy, and $$$ not to mention force of will when you really don't feel like eating that meal right now...).