One of the great advantages of podcast listening is the same advantage that the DVR offers -- the ability to time-shift programming. Also, depending on the method of listening to recorded audio, it can sometimes be played at (the more efficient) 1.5x speed.
With this great advantage, why have I always been intrigued with listening to shows on the live stream? In the past, when I was a heavy listener of the GSPN.TV podcast network, I got more than half of my audio from them via the live stream. Listening to the Katia & KylieMac live stream was something I did a lot, when it worked well into my schedule last year.
My current live stream listening includes the The Tony Kornheiser Show -- technically a local radio show that is also available via podcast. I also live stream the No Agenda Show show whenever possible, as well as a growing number of TWiT shows. Both of these networks have an app that allow me to listen to the live streams on my portable device, which I enjoy -- the other shows tether me to my computer, which is a disadvantage. Some live casts have chat rooms, but I don't often participate, so that's not the key. But time-shifting is such a great benefit, why are there times when I willingly give up that advantage?
Maybe the content is the key, as I consider the above list. Those shows that are more news-focused I tend to listen to via the live stream, while those that are less current-eventy I let wait.
Also the excellent new TWiT show, Mostly Photo, pretty much requires video, so watching the live stream on the computer makes more sense than watching it on the little iPod screen. But I don't watch a ton of videocasts, so that's only a part of it.
I should listen to everything via time-shifting, it's definitely more efficient. But still I do the live streams. And I'm not totally satisfied that I know why I do that.