Peer reviews are used by some companies as part of an employee's annual review process. In some cases, other "superiors" and lower level personnel take part in what has been termed the 360 degree process. The intent being to see how well the individual interacts with all levels of the organization.
Confidentiality of such information is up to the employer, usually documented in an employee handbook. In most cases I have seen, review information is not made public knowledge. The intent I suppose is that anonymity allows for free criticism without exposure to retaliation. How well it works, like any review system, is open to debate.
regards,