In the interest of science, I ran for about 15 minutes at various speeds in fifth gear to see what my oil temperature gauge reads. My car is a naturally aspirated 3.0 with a five speed transmission and the stock oil cooler and the ambient temperature was around 10° C (50° F).
80 km/h (50 mph): 93° C
100 km/h (62 mph): 98° C
140 km/h (87 mph): 105° C
200 km/h (124 mph): 125° C
full throttle: 140-150° C (didn't run 15 minutes because the oil was getting too hot)
I set the cruise control so that my GPS device showed I was traveling exactly those speeds. Interestingly, the cruise control could not be set above 200 km/h. Also, the water temperature gauge never showed an increased temperature. When the engine is warmed up my gauge points just above the third white line from the bottom regardless whether I'm going 90 km/h or 290 km/h.
The stock oil cooler does not have enough capacity to keep the oil at a stable temperature. I'm not sure how bad it is that the oil gets up to 140 or 150° C at full throttle since the oil temperature gauges on Audis and Ferraris have red zones starting at 150° C. Maybe modern synthetic oils can take it, but it doesn't make me very comfortable. In any case, I back off after a few kilometers at full throttle so that the oil doesn't exceed those temperatures and can cool down again.
With a supercharger, the engine will develop more heat and the oil temperature will increase faster. On hot days, the oil temperature is higher as well.