If you can, look at the article about strength training in the October 2005 issue of Running Times, by Jason Karp. This is very similiar to the program that I use for high school distance types.
The main idea is that during the offseason or early/mid base you do some work in the gym on peak strength. You can do upper body work year round if you want, but it doesn't work year-round on the legs when you are also doing high lactate running workouts (too long to recover). I would do squats in particular, 2 sets of 6 reps (not to failure) with 4-6 minutes rest, which is in the 80-85% of 1 rep max. You can also make significant gains in upper body if you do this, and you do it for a few weeks. What you get from this lower body work is higher strength levels, and greater ability to accelerate, and this turns into higher top speed when you start doing sprint/anaerobic work on the track.
Later, when you start to crank up the track intervals, you do what is known as ballistic weightlifting, or conversion to power if you follow Tudor Bompa. You do 2-3 sets of 8-10, but at 30-50% of 1 rep max, and you do the lift part of the exercise as rapidly as possible. This is like plyometrics, and it is not nearly as taxing as conventional weight lifting. This is the only type of weight lifting actually shown to increase running performance in experienced runners, and it does so through improved running economy.