Apple has sent an email to podcasters letting them know that it has revised its Podcasting guidelines.
"Since you’ve got an active podcast listed in iTunes, we would like to let you know about a few valuable new resources: First, the technical spec has been revised and expanded. Check here for all questions or problems related to your podcast, or if you’re interested in enhancing the appearance of your listing with iTunes-specific tags. There is also an Apple Discussions Forum exclusively for podcast producers, located here: If you have a question or a problem that the technical spec cannot answer, the community of iTunes podcasters there should be able to provide valuable guidance."