16 bit displacement has been supported for a while through the TIFF format. I think maybe Targa also. I know for a fact 16bit works because I'm the one at the office that begged for it. Sadly I should have been more specific, as PSD's that are 16 bit never seem to load. lol. Anyway, use TIFF, it should get the job done.

 

Edit: 32bit is still not supported as far as I'm aware.