Not by themselves, and it really depends on how well you listen to them.
Most podcasts that I listen to regularly are well written – the speaker is obviously reading from a script (or at least an outline) and has presented his/her thoughts in an organized way. You know – introduction, make your points, report your thoughts, and then say the conclusion.
This isn’t specific to podcasts – that’s how people tend to write (articles, essays, etc.) if they want to be understood.
So when you listen to podcasts, keep the following in mind:
1) how did they structure their talk (whether it’s 5 minutes or an hour).
2) did they use humor? not too much, not too little.
3) what about vocabulary? Are they using slang and jive, or are they talking to their audience in a way that they can understand?
and finally
4) pacing – not too fast and not too slow,
You can learn these skills from podcasts, but also from C-SPAN or anywhere else you have people trying to communicate with other people.