A podcast is just a feed of audio files on the Internet.
- You do not need an ipod to subscribe to a podcast feed, nor any other kind of feed. (Although there are some special tags that iTunes use with some feeds). A well written feed can be read by any modern browser (e.g. IE7+, Firefox, Chrome) or Thunderbird or iGoogle or MyYahoo or other feed readers.
In fact there are distinct advantages in not using an ipod when you subscribe to a podcast (e.g. ipods and itunes limit how the files are then played). Another advantage is that other mp3 players are usually lots cheaper. - You do not need to go through iTunes to subscribe to a podcast feed. Instead, manually add the feed address into your device. (in iTunes it is in the Advanced menu --> Subscribe to Podcast).