  Recently it has been understood that flavor-changing processes mediated by
Higgs bosons could be a new and powerful tool for discovering supersymmetry. In
this paper we show that they may also provide an important method for
constraining the parameters of the minimal supersymmetric standard model
(MSSM). Specifically, we show that observation of B_s -> mu mu at the Tevatron
implies a significant, model-independent lower bound on tan(beta) in the MSSM.
This is very important because tan(beta) enters crucially in predictions and
interpretations of the MSSM, though it is difficult to measure. Within specific
models, or with other data, the bound becomes significantly stronger.
