  We discuss Born-Infeld on the noncommutative two-torus as a description of
compactified string theory. We show that the resulting theory, including the
fluctuations, is manifestly invariant under the T-duality group SO(2,2;Z). The
BPS mass even has a full SL(3,Z)xSL(2,Z) U-duality symmetry. The direct
identification of the noncommutative parameter \theta with the B-field modulus
however seems to be problematic at finite volume.
