so called iTunes podcast format

There is no such thing as “iTunes podcast format”. Apple developped a module to the RSS standard.

RSS Modules : extend the basic XML schema established for more robust syndication of content.
http://en.wikipedia.org/wiki/RSS#Modules

Apple iTunes Module
http://apple.com/itunes/whatson/podcasts/specs.html#rss

See my previous post on Media RSS.

Going back to school

iTunes U
http://deimos3.apple.com/indigo/main/main.xml
You need to have iTunes installed for this URL to work properly as it links to a section in the iTunes Store.

YouTube EDU
http://youtube.com/edu

MIT OpenCourseWare
http://ocw.mit.edu