OT: What is a Podcast?
Here's a good definition:
According to the New Oxford American Dictionary, a podcast is "a digital recording of a radio broadcast or similar program, made available on the Internet for downloading to a personal audio player," but the generally accepted definition has expanded to include video as well as audio. Originally derived from a combination of "broadcasting" and "iPod ™," the word was declared "word of the year" when it was added to the dictionary at the end of 2005.
Basically you can upload it to your iPod.... some people do it -- like non-famous people doing topic podcasts from their home... and then some famous shows do it -- like radio shows, etc. You can usually search them on iTunes.
Elena gave a great answer and here's some more info that I used when writing a paper for grad school: Podcasting is an audio version of online blogs. The user can record material and then post it on the Internet for automatic play by other users. Podcasting uses include recording music recitals, journal activities, and announcements (Asmus, Bonner, Esterhay, Lechner, & Rentfrow, 2005, p. 9). We're starting to use podcasting in our school district to share lessons across schools (without having to physically move kids) and to share info with parents. Mary