In the past, video podcasts were also available in the Music section of your iPhone or iPod touch, and you could listen to their content content as audio only.
Since version 2.0, you can access video podcasts from the Music menu, but you can view their video now. You can also view them in both portrait and landscape mode.
[kirkmc adds: In this earlier hint, we mentioned that you would only get the audio of video podcasts when playing them from the Podcast menu. It's up to you to determine if this new behavior is good or bad.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080809155837992