Sen has shown that tachyon condensation in Dbrane--anti-Dbrane configurations can lead to remarkable connections between string theories. A consequence of his results is that there is a minimal value of the radial coordinate r_c∝(α′)^1/2(gN)^1/(9−p) such that N units of Dpbrane charge cannot be localized to values smaller than r_c. At this value of r_c the curvature is of order 1/α′ and the gradient of the Ramond-Ramond field strength is of order 1/(α′)^3/2, and the vacuum, regarded as a D-brane-anti-D-brane configuration with a tachyon condensate, is rendered unstable, leading to a separation of the D-brane and the anti-D-brane. This value of r_c lies in the region intermediate between the near-horizon regime and the asymptotic regime for D-brane classical solutions for small g. This vacuum stability bound on the curvature can be interpreted as an uncertainty relation for D-brane charge.