An extract from its wikipedia entry: Podcasting
'Podcasting' is a web-based broadcast medium. Audio files (most commonly in MP3 format) are made available online in a way that allows software to automatically detect the availability of new files (generally via RSS), and download the files for listening at the user's convenience.
The word 'podcasting' is a portmanteau of the words iPod and broadcasting. A podcast is like an audio magazine subscription: a subscriber receives regular audio programs delivered via the internet, and can listen to them at their leisure.
Podcasts differ from traditional internet audio in two important ways. In the past, listeners have had to either tune in to web radio on a schedule, or they have had to search for and download individual files from webpages. Podcasts are much easier to get. They can be listened to at any time because a copy is on the listener's computer or portable music player (hence the 'pod' in 'podcasting'), and they are automatically delivered to subscribers, so no active downloading is required.
Any use? Don't know, I'll give it a try currently have a couple, Microsoft News and Apple news from techpodcasts.com
and using iPodder
the premier Podcasting application, allowing users to capture and listen to Internet audio programs anytime, anywhere