This is a neat example of a podcast you can have your kids listen to learn more information about words: http://dictionary.reference.com/features/podcasts.html
Check out these sites (which helped me understand podcasting):
Podcasts could offer kids in classrooms the opportunity to listen to each others stories, share personal experiences about a shared topic of interest, or just give then another avenue to listen to information. Allowing kids the ability to hear or participate in a podcast, helps them realize that what goes onto the world wide web, really is indeed all over the world. Since there are 3 different types of podcasts (audio, video, and enhanced) you can offer your students a variety of new medias to learn.