Cardiovascular fitness is important in athletics but endurance training for sprinters is not the way to go about getting it. Sprints, tempo work, circuits, jump circuits, and even strength training will sufficiently train the cardiovascular system. Remember that even though most of the activities I just listed are predominantly anaerobic, the recovery from those activities has an aerobic component(you've probabaly noticed the slightly elevated HR after a 300m interval @ 90% :D). Also strength training has recently been linked with cardiovasular fitness despite the fact that it never elevates heart rate to any significant extent. In the end, while it is of some importance for sprinters (and all athletes) sprint and power training is typically more than enough to to provide adequate cardiovascular benefits.
Really, as with anything, you need to consider why you would want to do it. A sprinter doesn't have the same cardiovascular fitness requirements of an endurance athlete because they don't need such fitness to compete in their events. Not only that, the training that would be necessary to get that level of fitnes would actually hurt them by dulling their speed and diminishing strength and power. What cardiovascular fitness will do though is promote general health and serve as a better nutrient transport system which will aid in recovery. Specific training to develop it though is unnecessary.