It’s Gruber’s turn to beat the drum about what a ‘podcast’ is – and is not. You’ll not be shocked to read:
A podcast, to me, is a series of audio episodes available over the web. At a technical level, it’s an RSS feed, and the RSS feed has entries for each episode, and each episode has links to the actual audio file (in MP3 or AAC format, but usually MP3) and other metadata.
A definition any rational person could agree with.
See also: Music, Radio…Podcasts?