Thrown objects (eggs, snowballs, etc) will not work with minecarts in any recent Snapshot or pre-release.

So I decided to load up my survival world to one of the snapshots to see if I could get a mending enchantment. Of course, I needed the xp. So I head over to my zombie pigman farm, which requires snowballs to anger at least one pigman (the rest soon followed) So, as usual, I entered my Minecart tack that goes through the farm. However, when I preceded to throw a snowball at the target whom will anger any surrounding pigmen, it didn't seem to work. I later tried eggs as well, which didn't work. So I waited a few snapshots, then pre-release came. Did the same thing, and projectiles didn't work. I tried this with horses as well, does not work with horses.