I subscribe to far-too-many podcasts now, and I've found that most of the podcasters can actually be cleanly understood even if you speed up their speech by 50%. So, when my iTunes shows that I have 45 minutes left on a podcast, and I'd rather hear that in 30 minutes, I pull down my script menu to reveal and execute the following AppleScript (saved in my user's Library -> Scripts -> Applications -> iTunes folder as Play this song at 1.5x):
Basically, this tells iTunes to stop playing the podcast, figures out where I am in the podcast, then tells QuickTime Player to start playing the podcast at the same place (within a second), but at 1.5 times the speed. Note that the pitch is unaffected -- only the playback rate changes.
tell application "iTunes" pause set my_track to location of current track set my_seconds to player position end tell tell application "QuickTime Player" open my_track set my_movie to first movie set ts to time scale of my_movie set current time of my_movie to my_seconds * ts set rate of my_movie to 1.5 -- starts playing end tell
Mac OS X Hints