As noted by others this thread and many more throughout the forum, you can't "spot reduce" fatty deposits by concentrating on that area. That being said, doing ab workouts can strengthen the core muscles, and the bigger muscles may help reduce the appearance of the fat.
But in general, the problem areas of fats (which can be abs, thighs, buttocks, etc.) are usually the first to come and last to go, so a sensible and consistent diet and fat-burning exercise routine is needed to shrink 'em.
Current program: 1,800 calories most days of the week; 45-60 minutes of mixed exercises (weights, cardio-kickbox, dance, athletic intervals) 6 days a week
Current goal: 135 pounds by birthday (July 14th) and to run half marathon at end of May.