Maybe it is because I am more familiar with iTunes store but I really do like it better for finding podcasts. Podcastalley didn't give enough information about the podcasts and there were not any customer reviews. I have heard of this site before because certain podcasts want listeners to vote for them here so that their show goes up on the ratings listed on the side of the main screen. Podcast.net had categories to select from as well as a search bar and there were keywords to use also but again no reviews. Yahoo podcasts has ratings and I liked this one the best of the three. I found one library related blog that could be interesting and I linked it to my bloglines, Hennepin County Library Teenlinks Podcast. This podcast is created by teens for teens and could be something KDL could do also.
I actually listen to a lot of different podcasts and here are some of the book related ones:
Amazon Wire books, movies, music
Book Lust with Nancy Pearl
NY Times book reviews
Book talks with Nancy Keane
Just One More Book children's book reviews
NPR Books reviews authors etc
Plus I listen to a few different Harry Potter podcasts!