The interesting part about this phase of the Test Realm is that Hallow's End is up for testing! We might get to see Horseman mounts if the models that have been dug out of the game files are any indication, but we won't really know until we actually see them drop. Maybe they've gotten rid of the oh-so-phallic Broom mounts this time around? We'll find out, won't we?
If you're interested in checking out and testing Hallow's End before it gets pulled, you ought to hurry and get on the PTR. Brewfest was pulled after only a few days, so your time may be limited.
Edit: Never mind. See you in 5-7 hours!