  We show that a realization of the correspondence AdS_2/CFT_1 for near
extremal Reissner-Nordstrom black holes in arbitrary dimensional
Einstein-Maxwell gravity exactly reproduces, via Cardy's formula, the deviation
of the Bekenstein-Hawking entropy from extremality. We also show that this
mechanism is valid for Schwarzschild-de Sitter black holes around the
degenerate solution dS_2xS^n. These results reinforce the idea that the
Bekenstein-Hawking entropy can be derived from symmetry principles.
