As I found out today for interview podcasts a playback speed of 120% can make the interview much more fluid. Many people seem to speak quite slow when their processor and not just the quick-cache is working. For easy-to-follow and well-explained content this might unnecessarily slow down the listening experience, which impatient people (like me in this case) might want to avoid. This is where SoundStretch comes into play. With this Free Software tool you can add an extra 20% of tempo like this:

soundstretch -tempo=+20 <infile> <outfile>

What you get was a much more enjoyable podcast in my case.