We don’t use any special plugins to create enclosures. We simply add a custom field to each podcast post with a key of “enclosure” with the URL of the mp3 as the value. Usually WordPress makes the enclosure on its own automatically without needing a custom field, but not always. Adding the custom field guarantees that it will happen correctly every time.
We then use multiple categories to create feeds that contain just the right episodes we want. Our podcast currently has 6 different feeds for listeners to choose from. We filter all the feeds through FeedBurner to make sure the feeds are working, to track subscriber numbers, to offload stress on the server, etc.
Actually, I just ran into a problem. Using my method of creating a plugin by copying the edit-form-advanced.php into a plugin is not as perfect as it first appeared to be. While I am able to automatically fill in the title and post fields, there seems to be no way for me to automatically modify the categories or custom fields on the form. These areas on the form are generated by internal WordPress functions that I can’t seem to override or hook into. My only choice seems to be to re-implement those functions. Please tell me there is an easier way.