Little evidence for effectiveness of scientific peer review

Jen pointed to this BMJ Story on a systematic review {URL?} of peer review journals from the international Cochrane Collaboration.
They say despite its widespread use and costs, little hard evidence exists that peer review improves the quality of published biomedical research.
Published last week, the review is the third in a series from the Cochrane Collaboration Methods Group. The other reviews look at the grant application process and technical editing.