21st Century Competitiveness Act of 2007 - Expresses the sense of Congress that a robust National Aeronautics and Space Administration (NASA), funded at the levels authorized for FY2007 and FY2008 and at appropriate levels in subsequent fiscal years, would enable a robust and balanced set of programs in science, aeronautics, education, and human space flight and exploration, and allow full participation in any interagency efforts to promote innovation and economic competitiveness.