None of my running pals ever stretched before runs. We would simply start our runs real slow and let things warm up that way. Maybe we'd do a little mobilizing...like a cat or dog might do...but nothing else. Stretching afterwords was a different story...some did it and some didn't. We never noticed much effect either way.
As it turns out...our instincts might have been correct. This recent study showed that static stretching before running, decreased performance significantly...13 seconds on average in a one mile uphill time trial. This article does a great job of explaining it all.
It seems best to save the static stretching for after your running...and just do a bit of dynamic stretching beforehand as this article suggests. Just starting out your runs very easy may still be the best method.