I did a recent sample of some podcasts in my car with my Samsung Yepp plugged into a tape adapter that goes into my car stereo. 

Here are the audio levels of some of the shows sampled that I had to adjust on the car stereo (keeping the Yepp output at "20 out of 30"):

• Chuck Chat = 19
• Daily Source Code (DSC) Voice = 29
• Daily Source Code (DSC) Music = 23
• Future Tense = 23
• Jimmy Jett = 18
• Sound of the Day = 26
• Rock and Roll Geek Show = 15
• 5 Minute Max = 22
• OneMinuteTip = 22
• Todd Maffin = 21

Note I am not trying to pick on anyone … I didn’t listen to my own to figure out where should be.  But as "we" (big podcast community) moves forward we have to figure out a good way to get the levels right because "normal" people are not going to like making these adjustments all the time.

Maybe a future MP3 could handle this or maybe a "podcast service provider/distributor" could do this pre-delivery to the end user.