Playlists reside under the iPod repository node in the left hand pane of gtkpod. Clicking on them will display the tracks associated with them, effectively filtering the other gtkpod panes. You can ...
You have to download podcasts using a third party tool like http://linc.homeunix.org:8080/scripts/bashpodder/ or http://perli.net/projekte/gpodder/%29 .
Podcasts should be added directly into the 'Podcasts' playlist of the iPod repository, for example by selecting the Podcasts playlist before manually adding files/directories. Podcasts will then appear only in the Podcasts section on the iPod. If you add podcasts to the main playlist 'gtkpod/iPod' or any other iPod playlist first and then drag them over to the Podcasts playlist, the podcasts will appear in the Podcasts section on the iPod, as well as in the normal music section.
The podcast 'repository' is a local repository (like 'Local') where you can keep all local podcasts. No mechanism exists to automatically synchronize the iPod repository with the Podcast repository at this time. You have to drag the podcasts over manually.
If your ipod supports photos then a special dynamic playlist is created in the playlist tree. YOU CANNOT DELETE IT! Indeed when clicking on it all the usual track related ipod functions are disabled or removed.