There's actually a lot of new research going into tapeworm pills. Certain species can actually be beneficial and are not parasitic. Of course convincing people to take them is another issue...
What benefits are being touted?
Weight loss. They've been used for that for a very very long time. They can be effective but some side effects can be not to brilliant.( I think I'd prefer the stapler or good duct tape)
Tapeworm Diet Review
I'm skeptical of the "not parasitic" claim -- none of them have a digestive system so depend upon the nutrients they absorb.
What benefits are being touted?