Acoustic features distinguishing the male and female voice? I would like to use MFCC analysis to distinguish between a male voice and a female voice. 

Are there any particular quantifiable characteristics consistent with, and exclusive to, either gender? (E.g., energy, fundamental frequency, excitation, the presence of certain waveforms, etc.)
Main difference is the frequency of the fundamental, which is about an octave higher for women with the split point around 160 Hz or so. A fundamental lower than 160 Hz is most likely a male and a fundamental higher is most likely a female. A good overview over a number of studies on the topic can be found at http://www2.ling.su.se/staff/hartmut/f0_m%26f.pdf