iPad: getting back to initial screen after watching podcast
You don't specify if it's an Audio podcast or a Video podcast.

in a Video Podcast, the iPod App quits and Video app lunches with the selected Video Podcast, so when you press the DONE button you are in the Videos app

iPod-app



on tap on the Podcast, opens in Videos app

Videos app http://www.balexandre.com/temp/2010-09-22_0911_001.png

so, you can't go back because you are actually in other app... though the new iOS 4.2 makes that easy ;)