I had the corning lamp enabled on my Golf. Think some of the newer Golf/GTI VI 3 and 5 doors have this feature selectable in the MFI, but I didn't and had a friend enable it via the VAG-COM along with some other items.
For me, regardless of whether the signal light is on or off, with the steering wheel turned 90+ degrees (and in neutral or forward gears) the fog light on that side fades on and off. I think on the 3 and 5drs they are activated with the signal, but not 100%.
Living in the country, I find it very useful. Also, with high beams on the fog lights normally turn off automatically but even with high beams on when cornering the fog will turn on.
It won't light up street numbers on houses like an old Buick, Cadillac, or Lincoln would, but for the most part does the trick and I like the feature.