Surveillance, Tracking, Observation, and Prevention of Obesity Act of 2009 - Amends the Public Health Service Act to direct the Secretary of Health and Human Services (HHS) to: (1) make grants to 10 states for demonstration projects for the expansion of state registries on childhood immunization or health to include data on body mass index, collected and submitted to the state by health care providers; (2) require such registries to meet data standards and to be interoperable to ensure that registry data can be analyzed by the federal government and by other state governments; and (3) study and report on the effectiveness of such demonstration projects.