National Improvised Explosive Device Prevention and Preparedness Act of 2008

National Improvised Explosive Device Prevention and Preparedness Act of 2008 - Amends the Homeland Security Act of 2002 to establish the Office for Bombing Prevention, which shall have primary responsibility within the Department of Homeland Security (DHS) for enhancing the nation's ability, and coordinating its efforts, to deter, detect, prevent, protect against, intercept, and respond to terrorist improvised explosive device (IED) attacks. Transfers to the Office all functions of the current Office for Bombing Prevention of DHS's Office of Infrastructure Protection.

Directs the Secretary of DHS to ensure that a Homeland Security Advisory Council subcommittee, to be known as the Senior Advisory Committee on Improvised Explosive Device Prevention and Response, is established. Requires the Committee to: (1) provide policy guidance and recommendations; (2) develop best practices, training, and basic operational procedures; (3) promote interoperability and information sharing between the federal government and IED first responders; and (4) meet annually to review grant applications under the Bomb Prevention and Response Grant Program (established by this Act) and provide advice on proposed grant allocations.

Requires the Secretary's annual report on progress in achieving compliance with the correction of Coast Guard identified vulnerabilities in port security and compliance with Area Maritime Transportation Security Plans and facility security plans to include: (1) the identification of modifications necessary in funding to ensure the correction of capability gaps identified by the Coast Guard and the dive team component of the national analysis database on the capabilities of IED first responders (required to be maintained by the Office for Bombing Prevention); and (2) an assessment of progress in completing assessments for the dive team component for all applicable ports.