I feel that the problem here will be, as always, two-fold:
Getting it to work with short enough focal lengths to allow anything other than table-top product photography
Getting sufficient displacement to be meaningful BEFORE the depth of the mirror box vignettes.
For product shooting with a DSLR I don't believe you could do much better than the
PC Micro-Nikkor 85mm f/2.8D - it is certainly one which I am considering very strongly in my proposed switch to digital.
Nikon pioneered the concept of the PC lens with its 35mm and 28mm lenses. The challenge was taken up by Canon, of course with their three tilt/shift lenses (24mm, 45mm & 90mm). I can understand why there have not been any new wide angle developments suitable for the APS sized chip - to begin with the already problematic issue of the angle of incidence of image forming light on the sensor would be further exacerbated - but I DO live in hope.
Cheers,