Originally Posted by sic
iTunes is able to pick up the PDF from the newsfeed. (hmm... is Apple preparing for something?)
A podcast is nothing more than an RSS feed which has an enclosure (file) specified in the feed. For a podcast that enclosure is usually an .MP#, .AAC or other audio file. However, the enclosure can be any file type, it can be a MPEG (movie) or as you found a PDF. RSS is started being used for alot more than delivering text, stuff like MAPs, Traffic reports, pictures, etc.