Alright Probiotics are now all rage on TV. You see them especially in yogurts. Probiotics are the good bugs; Lactobacillis acidophilus (works in small intestine) & Bifidobacterium bifidus (works in the large intestine) plus the super food called fructoligosaccharides (FOS) for the good bugs have to stable and make it to the intestine to work. In my opinion, if you want the benefit of Probiotics take a stable freeze-dried product like Probiotic Plus (where you need only ONE capsule to move waste). If you are looking for some healthy yogurt choices for a snack; Dannon's Light & Fit or Nancy's Yogurt are excellent choices.
I think the yogurts touting that they have live cultures in them are expensive marketing hype and very few "live cultures" get through to do their jobs in the intestine.