I caught the Drake reference too, but I don't recall that Drake factored in the odds of extinction. Maybe that was Sagan's contribution to the equation?
Actually, the Drake Equation was intended to estimate how many intelligent civilizations might exist in our galaxy (or the the universe as a whole) that have technology enabling us to receive their radio emissions by means of a radio telescope. One of the variables measures the time that intelligent, radio-communicating inhabitants of a planet survive before destroying themselves. I think that this concept was part of the original Drake Equation.
See, for example, this link for more:
http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html