See the difference in this video posted a year ago http://www.youtube.com/watch?v=sfLHojgVYtk and this one posted 3 months ago http://www.youtube.com/watch?v=rdUXYPBQG-M. I understand that Philip Garber has been taking speech therapy, and it sure has helped him. It also shows that his stuttering is not near as "disruptive" in a classroom as it would have been a year ago.
A few people who stutter say that speech therapy did not help them or even made them worse. I expect they did not have a therapist who was trained to work with stuttering. If you or your child stutters and you are seeking a therapist, make sure they have been trained to work with someone who stutters. If there is not one near you, there are summer camps and intensive clinics run by good therapists. You can find the lists under "referrals" at www.stutteringhelp.org