Oh great! Removing the 1D4 from the Canon Professional Imaging Products page means that they are probably done supporting this model with Firmware updates. I guess it was inevitable with the release of the 1D X.
http://www.usa.canon.com/cusa/professional/products/professional_cameras/digital_slr_cameras/eos_1d_mark_iv
http://www.usa.canon.com/cusa/professional/products/professional_cameras/digital_slr_cameras/eos_1d_mark_iv