To my mind, podcasting isn't about sending files to a pod, it's about sending files in a pod.
The files need a container, something to tell them which order to play in, and a means of distribution.
The easiest way is to take some MP3s, put them in a folder, add an M3U playlist, zip up the folder and put it somewhere online (eg yousendit or your own server).
Alternatively, don't zip up the folder but instead turn it into a torrent (eg with Azureus) and distribute it that way - this has the advantage that people can keep sharing at the same time as playing.
Another alternative is to make the playlist implicit and concatenate all the files into one big MP3. This is ideal for dealing with iTunes, which is terrible at handling playlists, and is also good for podcasting via RSS (see the 'Download to iTunes' option in NetNewsWire). Radio shows and long mixes work well this way.
Or just distribute a playlist that fetches in the files from a remote location. Putting MP3s in a folder on your server and pointing Playr at that folder (or a blog post linking to the files in that folder) will generate a playlist in MP3, SMIL or Flash/XSPF format that anyone can play while online.
Finally, there's the possibility of distributing a playlist containing only the barest of details about each track: artist name, track title, track duration, etc... Kazaa had Kapsules, Shareaza had Collections and Rhapsody has its own playlist format, but they're all restricted to certain modes of file transfer. In theory, an XSPF playlist with this metadata could allow anyone with access to a capable resolver to find and play the podcasted tracks by whichever means they have available.
As an example, here's a pod in multiple formats: m3u pod smil pod flash pod zip pod mp3 pod
and a tracklisting:
- Caribou - Hello Hammerheads (from The Milk Of Human Kindness)
- Oneida - Lavender (from The Wedding)
- Todd - Butlers Portion (from Purity Pledge)
- Art Brut - Modern Art (from Bang Bang Rock and Roll)
- Do Me Bad Things - Time For Deliverance (from Yes!)
- Vitalic - My Friend Dario (from OK Cowboy)
- The Duke Spirit - Cuts Across The Land (from Cuts Across The Land)
- Sons And Daughters - Medicine (from The Repulsion Box)
- The Plot To Blow Up The Eiffel Tower - SLC Hunks (from Love in the Fascist Brothel)
- A Frames - Galena (from Black Forest)