Can Rectangle pot PVRTC textures be used on iOS?

The PVRTexTool is able to compress rectangular textures into the PVRTC format. These textures work fine in the Editor, however when the build is deployed to an iOS device (I tested with an iPad2), all the meshes that use rectangular PVRTC textures show as pure black.

Is there a proper way to coerce Unity to use these textures? Are there any known hacks, otherwise?

http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/TextureTool/TextureTool.html

Important: If you are using PVRTexTool
to compress your textures, then you
must create textures that are square
and a power of two in length. If your
application attempts to load a
non-square or non-power-of-two texture
in iOS, an error is returned.

This is a driver issue, not a hardware limitation. (At least for current hardware, the MBXLite didn’t support non-square PVRTC.) Maybe try pestering Apple about it.