I have been having a similar problem. I bought the Smith Turbo and both my glasses (with Cat Crap) and the goggles fogged up (even on Turbo mode) so I returned them.
I figured out I was overdressed, so I have lightened up the clothing and head protection and had some initial success with a regular pair of Smith OTG goggles. However this week I am running into the same problem.
Can you update me on your innovation now that colder temps are here. Listed below is some info from my recent rides.
Date Air Deg F Wind Chill Deg F DP Deg F Fogging Comments
11/26/2008 19 11 16 No Felt great coming in to work!
12/1/2008 25 12 19 Yes Glasses fogged some - did not use Cat Crap
12/2/2008 12 -2 10 Yes Glasses fogged, eventually I had to remove goggles to safely ride, the glasses still fogged, but I was able to see.