Perchlorate Monitoring and Right-to-Know Act of 2008 - Amends the Safe Drinking Water Act to direct the Administrator of the Environmental Protection Agency (EPA) to: (1) publish (within 90 days) a health advisory for perchlorate that is fully protective, with an adequate margin of safety, of the health of vulnerable persons (including pregnant women, infants, and children), considering body weight, exposure patterns, and all routes of exposure; (2) propose (within 60 days) and promulgate (within 120 days) a final regulation requiring public water systems to monitor for perchlorate, which shall be in effect until monitoring for perchlorate is required under a national primary drinking water regulation; and (3) require consumer confidence reports by community water systems to disclose the presence of perchlorate in drinking water and the potential health risks to vulnerable persons.