Actually, the current 'enhanced' podcasts are Apple proprietary (afaik), though I've done some initial work on reverse engineering them. I'd like to get them in eventually, but it's a ton of work (parsing mp4 files isn't fun without a random access filesystem to work with).
Wish I had a better answer for you...
-Marcus
Versatile Monkey For more/quicker help make sure to check out the user manuals