Below are some excerpts on the research that has been done. I will say that as crazy as the drug laws here, at least they were able to conduct the research.
Hopkins study on personality changes:
Lasting change was found in the part of the personality known as openness, which includes traits related to imagination, aesthetics, feelings, abstract ideas and general broad-mindedness. Changes in these traits, measured on a widely used and scientifically validated personality inventory, were larger in magnitude than changes typically observed in healthy adults over decades of life experiences, the scientists say. Researchers in the field say that after the age of 30, personality doesnt usually change significantly.
http://www.hopkinsmedicine.org/news/media/releases/single_dose_of_hallucinogen_may_create_lasting_personality_change
OCD Study:
In a controlled clinical environment, psilocybin was safely used in subjects with OCD and was associated with acute reductions in core OCD symptoms in several subjects.
http://www.ncbi.nlm.nih.gov/pubmed/17196053
Cluster headache study:
Twenty-two of 26 psilocybin users reported that psilocybin aborted attacks; 25 of 48 psilocybin users and 7 of 8 LSD users reported cluster period termination; 18 of 19 psilocybin users and 4 of 5 LSD users reported remission period extension.
http://www.ncbi.nlm.nih.gov/pubmed/16801660
OCD and cluster headaches are both really, really horrible conditions. The fact that people have to continue to suffer because others might want to use some of the beneficial effect of psilocybin is insane.