Frictionless Insight also has a preview, in which they say the four animal bosses will consist of Bear, Eagle, Lynx, and Dragon Hawk spirits. Strangely enough, we've already heard that there will also be a "god of evil" as well as a witch doctor and the end boss Zul'jin, which means there may be more than the six bosses that Blizzard first hinted at. Additionally, we've heard from quite a few sources now that the Zul'Aman trash will be very sociable (as in, there will be mobs that bring more if you're not careful), but Frictionless Insight says the dungeon itself will start with a boss, not trash, so even more good news for most raiders.
All in all, Zul'Aman seems to be shaping up nicely. There's no telling when we'll see it on the PTRs, but I would be very surprised if Blizzard didn't let us play it (or at least see a preview of it) at Blizzcon. Storm the castle!