In Peer Review, scientific articles are vetted by scientific colleagues.
Difference between Communal Validation and peer review
Peer production is based on equipotential participation (see Equipotentiality, i.e. the a priori self-selection of participants, and the communal vetting of the quality of their work in the process of production itself. Peer review is based on credentialism, peer production vetting is based on Anti-Credentialism. Peer review is part of an elaborate process of institutional and prior validation of what constitutes valid knowledge; peer production vetting is a posteriory vetting by the community of participants.
A quote on the difference between peer to peer processes and academic peer review:
“One of the early precedents of open source intelligence is the process of academic peer review. As academia established a long time ago, in the absence of fixed and absolute authorities, knowledge has to be established through the tentative process of consensus building. At the core of this process is peer review, the practice of peers evaluating each other's work, rather than relying on external judges. The specifics of the reviewing process are variable, depending on the discipline, but the basic principle is universal. Consensus cannot be imposed, it has to be reached. Dissenting voices cannot be silenced, except through the arduous process of social stigmatization. Of course, not all peers are really equal, not all voices carry the same weight. The opinions of those people to whom high reputation has been assigned by their peers carry more weight. Since reputation must be accumulated over time, these authoritative voices tend to come from established members of the group. This gives the practice of peer review an inherently conservative tendency, particularly when access to the peer group is strictly policed, as it is the case in academia, where diplomas and appointments are necessary to enter the elite circle. The point is that the authority held by some members of the group- which can, at times, distort the consensus-building process - is attributed to them by the group, therefore it cannot be maintained against the will of the other group members." (Felix Stalder in: http://news.openflows.org/article.pl?sid=02/04/23/1518208 )
Lessons from the History and Philosophy of Science regarding the Research Assessment Exercise. URL = http://www.ucl.ac.uk/sts/gillies/
This article by Prof. Donald Gillies shows examples of why an excessive reliance on peer review can impede scientific progress, as major advances were in their time rejected by their peers.