This is a random bug that seems to happen to me from time to time, but this morning it's happened more than once.
When I subscribe to a new feed, the first item in that feed (usually I'm subscribing to a feed from Podiobooks.com and there's only one item in the feed since I have them only release one new item per day in each book feed) will get placed into the wrong playlist when synchronized to my iTunes library. Also, it will have it's title changed to the corresponding first entry in the wrong podcast's feed.
Example:
I have a subscription to Podcast X, which is long-running and (let's say) is on episode 15, with no problems.
I subscribe to Podcast Y, set it up to sync with the library in the sync tab, and save that option using the save button in the toolbar.
I want the first episode, so I go and manually start the download by right-clicking on the first item in Podcast Y and choosing "Get Enclosure".
When it's done downloading, it get placed in the already existing playlist for Podcast X. Also, it has had it's title changed to the title of the first item in Podcast X's feed.
If I had to make a guess, it seems like it might be a bug in code which is checking for an already existing playlist in iTunes, if such code exists. The wrongly chosen podcast seems to always be next to or within 2 spaces of the new podcast alphabetically, and if I remember correctly, almost always lower than the new podcast alphabetically, though I can't be 100% sure on either case.