Lately S-berg's been making a lot of films with this neat bleach bypass/bluish desatured effect where the whites/highlights seem blurred and diffused... I.E. Munich/Minority Report/War of The Worlds/ How does one in FCP using their color correction tools do something along the lines of blurring JUST the whites/highlights witha kind of gaussian diffusion? I apply gaussian blur to a clip sometimes/layer it ontop a duplicate then do blending modes like screen/soft light, but it blurs everything in the color spectrum, I just want to isolate the whites/highlights to create a glowing/halo effect like spielberg is doing lately, I know there's a way to do it, could someone please detail this process?

You're on the right track, but instead of using transfer functions apply a chroma or luma key and isolate the areas you want to blur.

The easy method is to use Magic Bullet for Editors. You can download the demo plugins at http://www.redgiantsoftware.com/mbforeditors.html

I think you'll actually get a smoother result sticking with the transfer modes - but the trick is to add in a levels or contrast filter to push the stuff other than the highlights close to black before blurring the highlights.