I agree totally with the comments of CTR1, i've just finished my final year in sports therapy at uni, and i completed my dissertation in this area. Dymanic exercise and 'practice' (or low weight sets) have been shown to increase power measurements, with static stretching decreasing power.
Stretching should be purely a personal thing (purely because people have been told for as long as they can remember that static stretching prevents injury and helps, and trying to change this mode of thinking is near on impossible). There are people that will never suffer an injury in their lives and have never completed a warm up. However, scientific evidence would point towards decreasing static stretching during warm ups, and this is shown by the fact that there are very few professional teams in any sport that use static stretching these days during a warm up. I believe we in England are years behind the Aussies and Americans in this department!
I would quite willingly place money on static stretching having no impact on injury prevention, you'd be much better off spending time working on your fitness, posture and technique, as these are areas that appear to be more likely to be linked to injuries. Fitness and muscle conditioning is a major factor, purely because fatigued muscle contract and become tighter, leaving them more vulnerable to injury.
IMO, Static stretching is best left to post exercise and should also be used as a seperate training component, if it is felt this is needed. Strength training will also help to increase flexibility, for those that are interested! It's due to golgi tendon organs which cause the muscle to decrease it's tension to protect the muscle from injury, strength training obviously increasing tension in the muscles.
To cut my long post short, stretch if you feel you need to, but i personally keep it to a minimum, unless i have a really tight muscle that is bugging me.