If you really want your podcast converted from audio to text, a service is now available for you to get it done. From their site...
PodClerk.com offers transcription of your own or your favorite podcasts into a plain text, html, rtf, pdf or even xml.
Just submit the URL of your podcasts (.mp3 or rss feed) and receive your transcriptions on your e-mail, usually, within 24 hours.
The only downfall I see right now is their price. It will cost you $0.34 cents per minute for regular transcription and $0.40 to get it done in a rush (not to mention there is a 30 minute minimum meaning each file will cost you at least $10.20 to have done).