Looks like iPhone 3.0 Beta 5 doth giveth a little as well. That tiny email icon present in the top navigation bar of podcasts was decorative only until Beta 4, when it began to allow you to email the iTunes Store link for a friend for any podcast you'd downloaded over-the-air (at least for some it did). Now, with Beta 5, that tiny email icon is powered up and working for podcasts synced over via iTunes as well.
Earth shattering? No. But if you're enjoying a great episode of Phone different, GDGT, TWiT, YLNT, or whatever else floats your audio boat, and you want to give a friend easy access to equal entertainment, it's certainly a great convenience.
[Thanks anon for the tip!]