Research says not!
A study recently published in the Journal of Strength and Conditioning Research (1) looked at the effects of specific abdominal exercise on anthropometrics, body composition, and abdominal muscular endurance for 5 days a week for 6 weeks, as compared to a control group. All subjects followed the same diet during the study.
The results showed that there was no significant effect of abdominal exercises on body weight, body fat percentage, android fat percentage, android fat, abdominal circumference, abdominal skinfold and suprailiac skinfold measurements in the abdominal exercise group compared to control. Indeed, the only difference between the two groups was the ability to perform a significantly greater amount of curl-up repetitions in the abdominal group.
So what does work for reducing abdominal fat?
If you want to beat the abdominal bulge, take note of the hierarchy of fat loss:
1) Good Nutrition (you can't out train a bad diet)
2) Resistance training: compound movements under load recruit maximal muscle fibres and illicit a large metabolic response - think squats, lunges, deadlifts, overhead presses, pull-ups and pull downs, for example..
3) high intensity interval training, interspersing fast bursts of exercise with low intensity rest periods
4) low intensity interval training
high intensity steady state exercise
5) Low intensity steady state exercise
(1)The Effect of Abdominal Exercise on Abdominal Fat. Vispute, Sachin S; Smith, John D; LeCheminant, James D; Hurley, Kimberly S Journal of Strength & Conditioning Research: September 2011 - Volume 25 - Issue 9 - pp 2559-2564 doi:10.1519/JSC.0b013e3181fb4a46