Looks like Call of Duty will tweak to widescreen the same way you would with the Quake 3 Engine.
I chaned the 'config.cfg' file in the same way as the Quake 3 thread, and it works.
Although I left the FOV setting where it was. Which was 80. When I changed it to 115, it looked very weird when turning.
Shot001 - 1680x1050 with FOV 80
Shot002 - 1680x1050 with FOV 80
Shot003 - 1680x1050 with FOV 115
Shot004 - 1680x1050 with FOV 115
Sorry if they are too big. Put it to the max resolution of my monitor.
Only thing is, when you run the game it pops up a window asking about letting it 'Set Optimal Settings'. Say no, or the changes you made go bye bye.
EDIT: Also, the intro movies DO NOT play. So you can also change the com_introplayed from '0' to '1' to bypass the intro and go directly to the menu screen.
I found a site that says adding '+set r_optimize 0' to your shortcut removes the warning. BUT, they are not specific on what exactly this could impact. I tried it and do not see anything yet to mess up gameplay. So use this all at your own risk. 8)