It will be at SMU:

Representatives of President Bush announced this afternoon that Southern Methodist University in Dallas will be the home of the library housing his presidential papers and a public policy institute. …
SMU, the alma mater of first lady Laura Bush, was chosen over several other institutions to house the library, including Baylor University, the West Texas Coalition, the City of Arlington, Texas A&M, the University of Texas, and the University of Dallas.
Bush has been close to settling on SMU for roughly a year, but it has taken time to work out the details. There’s also been controversy over the presidential project in Dallas, with some Methodist leaders opposing the project and some faculty members complaining about the university identifying itself too closely with the Bush presidency.