Obligatory warning: This script has been designated as an obsoleted "Retro Script". There is no guarantee that it will function as described with modern versions of iTunes and OS X. If used in its current form it may not work at all without modification and, at worst, it may corrupt or destroy data.
iTunes will stop updating a podcast if you have not listened to at least one of its episodes in five days. This script will batch-update every podcast subscription so you don't have to manually update each one individually.
I have posted instructions on how to create a launchd agent to run this script automatically and invisibly in the background to ensure that your Podcasts are always updated.
Possible iTunes bug (July 17, 2014): Looks like the iTunes AppleScript command updatePodcast command is broken as of iTunes 11.
downloaded 35s ago
Renumber order of selected tracks
downloaded 8m 32s ago
Copy chosen tag info from one set of tracks to a different set of tracks
downloaded 14m 31s ago
Set the Plays of selected tracks.
downloaded 15m 24s ago
Prefix each selected track's Song Name with the number of its order in the selection.
downloaded 16m 52s ago
Re-locate files of selected tracks to new folder, preserve track meta-data
downloaded 18m 55s ago
Gather audio tracks whose files contain no artwork metadata