The question is how do we develop this power?
The NSCA's Essentials of Strength Training and Conditioning (Baechle, 2000) says that the most important method to develop power in the weight room is by using a medium-heavy load somewhere in the repetition range of 3-6 reps. This is derived from the Force-Velocity Curve which measures the amount of force a muscle can create at different speeds of contraction. The 3-6 repetition range is the range typically involving the most power production. Basically, if you can move 50 pounds at 10 mph and a week later at 12 mph through the same range of motion, you have become stronger.
Charles Polliquin, a well respected Canadian Strength and Conditioning coach, has theorized that to become more powerful, you in fact want to work the entire length of the Force-Velocity curve. Therefore, you would have some days of moving light weight with a lot of speed, some days moving a lot of weight slowly, and other days spent anywhere in between. I think this premise is based on developing both muscle tension potential (amount of force potential) as well as contractile speed (time for muscle contraction). The resultant of these two phenomenon is a more powerful curve overall, and thus a more powerful athlete.
The next question you may ask yourself is: What is the appropriate time of year to strength train for increases in Power?
I think you can work on power development in the weight room at many times during the year, but the most appropriate time would be during the preseason. This seems like a good time to decrease the overall load slightly (who cares about maximum strength), and concentrate on moving with speed in preparation for competition. with that being said, if you are a coach trying to develop Power, I certainly hope you are also devoting time to overall strength, strength maintenance, hypertrophy, and recovery during you're athletic season. In addition, a periodized plan needs to be implemented for each of these phases.