MAKe had an interesting article about how you can create a podcast that -- instead of music -- will contain PDF files.
They're using it to distribute their magazine.
iTunes is able to pick up the PDF from the newsfeed. (hmm... is Apple preparing for something?)
I've given it a try and it works great.
You need a blogging software that lets you upload files ang generates a newsfeed for it. I've been using YACS (YetAnotherCommunitySystem) and it works fine.
This would let people create their on magazines in PDF, post them on a website and create a podcast newsfeed for it.
Then readers would subscribe to the feed via iTunes (and maybe later with Connect Reader, when SONY wakes up) and there you go!