Yeah, I'm interested in this too. Unity 3d is one game engine you can look at to get more ideas of iphone's capabilities: http://unity3d.com/unity/whats-new/unity-2.5
If you are working with unity you can try the "strumpy shader editor" its free. The only problem is that it is only supported til unity 3.5. But the compiled shaders should still work with unity 4.
With PBR workflows, usually not. Unless some dumbass decides to use viewport renderer in c4d or 3DS max. Unless it's unity. Unity has this very distinct deep fried smooth look to it. Something about the color management & lighting system in unity is just outright incorrect. No, it's not just set up wrong, or the wrong use…
Is there any kind of limitation related to the differences between Unity pro and Unity free ? For instance and if I remember correctly, Unity free does not support cast shadows. So what happens when Skyshop is being plugged into Unity free ? Would cast shadows (as seen in the Vespa screenshots) actually appear in the scene…