I have to say first of all that this idea isn't mine-- it came from this post by Cosmonut over on AppleInsider's forums (I found it during one of my many Google searches while trying to figure this out). But here's my explanation of how to do it-- I wasn't able to find an easier way. Basically, what you'll do is make a bunch of different smart playlists for each podcast you want to use, with one show each, and then automatically combine them into one master playlist that will update itself every time a new podcast shows up.
First of all, obviously, you have to subscribe to the podcasts you want to download. I rounded up a few of my favorite daily podcasts, with the plan of putting them all together so I'd have something to listen to as I woke up in the morning.
Next, what you'll want to do is create a Smart Playlist for each of the podcasts you'll want to include in the master playlist. Create a smart playlist, and then set Podcast to "true," (see below for the settings) and change the Album to whatever your playlist's Album is (I had to "Get Info," or ⌘
-I, on a few of the shows to figure out what they used for an Album identifier).
Finally (and this is the key), you'll want to check "Limit to," and limit the playlist to one item selected by "most recently added." That will give you a playlist with only one item in it: the most recent show iTunes has downloaded for you.
When you're done with all of this, you'll have a smart playlist for every show you want in the master playlist, and each one will have just one episode (the latest one you've downloaded) in it. For convenience's sake, I put all of these playlists into one folder.
Finally, you can create your master playlist, which is the actual playlist I'm going to have Awaken play for me every morning. To do that, create another smart playlist, and then just put in all the playlists that you've created so far.
And as you can see, since each playlist only has one episode in it (the most recently downloaded), you end up with a master playlist of all the latest episodes of these podcasts. Since all the smart playlists are updated live, when a new podcast gets downloaded, the show's playlist will change, and thus the master playlist will also bring in the new show.
Pretty convoluted for iTunes (although podcast playlist support has never been great anyway). But it does exactly what I wanted to do: put all the latest daily episodes of my selected playlists into one list ready for me to play automatically each morning as I wake up and brew the coffee.
Update: Hessi in the comments makes a good point-- the folder you put the playlists in itself should work as a playlist for the purposes of playing the podcast, so you may not have to create a master playlist at all. But I'm not sure that folders work exactly the same as playlists in all instances (on iPods, during syncing, etc.), so it might be worth creating a separate master playlist anyway.