  Considering gravitino dark matter scenarios, we study constraints on the
reheating temperature of inflation. We present the gauge-invariant result for
the thermally produced gravitino yield to leading order in the Standard Model
gauge couplings. Within the framework of the constrained minimal supersymmetric
Standard Model (CMSSM), we find a maximum reheating temperature of about 10^7
GeV taking into account bound-state effects on the primordial $^6$Li abundance.
We show that late-time entropy production can relax this constraint
significantly. Only with a substantial entropy release after the decoupling of
the lightest Standard Model superpartner, thermal leptogenesis remains a viable
explanation of the cosmic baryon asymmetry within the CMSSM.
