  The increase in discovered close binary central stars of planetary nebulae is
leading to a sufficiently large sample to begin to make broader conclusions
about the effect of close binary stars on common envelope evolution and
planetary nebula formation. Herein I review some of the recent results and
conclusions specifically relating close binary central stars to nebular
shaping, common envelope evolution off the red giant branch, and the total
binary fraction and double degenerate fraction of central stars. Finally, I use
parameters of known binary central stars to explore the relationship between
the proto-planetary nebula and planetary nebula stages, demonstrating that the
known proto-planetary nebulae are not the precursors of planetary nebulae with
close binary central~stars.
