A bill to amend the Public Health Service Act to reauthorize the Community Health Centers program, the National Health Service Corps, and rural health care programs.

Health Care Safety Net Act of 2008 - (Sec. 2) Amends the Public Health Service Act to reauthorize appropriations for FY2008-FY2012 for health centers to meet the health care needs of medically underserved populations.

Requires the Comptroller General to study the economic costs and benefits of school-based health centers and their impact on the health of students, including an analysis of: (1) the impact that federal funding could have on the operation of such centers; (2) any cost savings to other federal programs derived from providing health services in such centers; and (3) the impact of such centers in rural or underserved areas.

Requires the Secretary of Health and Human Services, acting through the Administrator of the Health Resources and Services Administration (HRSA), to submit a report to the relevant congressional committees that describes efforts to expand and accelerate quality improvement activities in community health centers.

Requires the Administrator to establish a mechanism for the dissemination of initiatives, best practices, and other information that may assist health care quality improvement efforts in community health centers.

Directs the Comptroller General to study integrated health system models for the delivery of health care services to medically underserved populations.

(Sec. 3) Reauthorizes appropriations for FY2008-FY2012 for: (1) the National Health Service Corps program; and (2) the National Health Service Corps Scholarship Program and National Health Service Corps Loan Repayment Program.

Repeals provisions requiring each center or clinic designated as having a health manpower shortage to demonstrate every six years that it meets the applicable requirements of the definition of a health professional shortage area.

Revises requirements for assigning members of the Corps to a health professional shortage area to require that the Secretary determine that an entity demonstrates willingness to support or facilitate mentorship, professional development, and training opportunities for Corps members.

Requires the Secretary to assist Corps members in establishing and maintaining professional relationships and developmental opportunities.

(Sec. 4) Reauthorizes appropriations for FY2008-FY2012 for grants for expanded delivery of health care services in rural areas, for the planning and implementation of integrated health care networks in rural areas, and for the planning and implementation of small health care provider quality improvement activities.