I just took 2 screenshots. One with 75 and another one with 90, there's no difference at all.
http://img181.imageshack.us/f/beforegl.jpg/
http://img37.imageshack.us/f/afteri.jpg/
As you can see there's no difference. What am I doing wrong? I am changing the Falloutpref.ini fDefaultFOV=75.0000 to fDefaultFOV=90.0000 and there's no change at all in FOV.
I believe the engine adjusts general FOV on its own, the fDefaultFOV value is for terminals, lockpicking, other 'interface' devices (like the SPECIAL machine at the beginning), and maybe binoculars.
This is most pertinent to high resolution displays, ordinarily you don't really need to make adjustments.
If you're interested, the Widescreen Gaming thread is here - http://www.widescreengamingforum.com/forum/viewtopic.php?f=57&t=20661
And there's a thread on the hardware board here - http://www.gamesas.com/index.php?/topic/1122530-multi-screen-resolution-support/
You should also make whatever changes you want to the default.ini in the Steamapps folder, since it seems to be overriding the other ini's at the moment.
-HD