A colleague contacted me with an iTunes/Podcasts/iPhone/iPod conundrum that goes a little something like this:

I have my iPhone set to sync "All New" of "Selected Podcasts." If I listen to part of a podcast episode on the iPhone, then sync it to my Mac, the episode gets deleted from the iPhone. What's up?

Regrettably, the way iTunes defines "new" is not, "most recent" but rather "most recent that you've never played any portion of." It's like this:

Let's say you've told iTunes to sync the three most recent new episodes of our very own Macworld Podcast. Once you've started playing one of those episodes on your iPhone or iPod, it's no longer considered new. And because it's not, it's booted off the device when you next sync and marked in iTunes as not new, even though you may have listened to no more than a couple of seconds of it. You can put it back on by moving to the podcast episode within iTunes, right-clicking on it, and choosing Mark as New from the contextual menu, but yeesh, what a bother.

If you'd like to keep those episodes until they are completely played, you should choose to sync the X most recent unplayed episodes of your podcasts. A podcast episode isn't considered "played" on an iPhone or iPod until it plays to the very end (and yes, you can work around this by fast forwarding the podcast to the last few seconds and then letting it play out).