AutoCAD 2007 catches up to IntelliCAD by coloring the x, y, and z axes: red, green, and blue. If you want to go back to all-black, turn off the Tint for X,Y,Z option in the Drawing Window Colors dialog box (Options | Display | Colors).
Taking a step beyond IntelliCAD, the new AutoCAD also allows you to change the labeling of the axes. You can have x,y,z or N, E, z or any label of your own, up to 8 characters in length. You make these changes in Options | 3D Modeling (look at the 3D Crosshairs area).