Podcasting is still at the beginning of its adoption cycle.

Simply posting audio files on the internet for download is NOT podcasting.
The power of podcasting comes from a subscription model, commonly using RSS technology (Really Simple Syndication). Listeners use free software such as Appleā€™s iTunes, or any simple RSS reader (also popular for reading blogs) which periodically checks for and retrieves new audio content automatically.
People can then listen to the audio on their computer and copy the audio files onto an iPhone, iPad, iPod (using software such as iTunes) or similar mp3 player or mobile device.

Podcasting is becoming increasingly popular due to the rapid increase in the use of portable media devices, as well as a new generation of wireless phones. Consumers prefer to listen to WHAT they want, WHEN they want it. This allows storage of fresh new content that can be enjoyed later – at the gym, in the car, etc. Most podcasts are free to subscribe to, and easy to download.