Canon has issued firmware v1.1.1 for its flagship EOS-1D X full-frame DSLR. The update adds three options for indicating the selected AF point when in AI Servo autofocus mode. This includes red illumination, rather than just darkening the selected point, making the camera easier to work with in low light. The update also allows the central AF point to act as a cross-type point when working with lens/teleconverter combinations that give a maximum aperture of F8. This capability is currently only available with F5.6 (or brighter) combinations.
News: Digital Photography Review (dpreview.com)