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Are there any situations in which it makes sense to raise the ISO in bright daylight?
I was looking at this image (from From Reuters blog http://blogs.reuters.com/fullfocus/2012/11/30/best-photos-of-the-year-2012/#a=3): 
Is there a reason why the photographer choose to shoot at ISO 800, f2.8, 1/500? Couldn't he shoot at ISO 200 1/125 and get the same result with less noise? (I'm not saying the image has a lot noise, it doesn't have, just curious about the settings).
Answer
I used to think the same way, but then I realised how slow ~1/100s shutter really is. In my work as a machine vision engineer I am used to thinking of the shutter as milliseconds, rather than as fractions and for dynamic subjects (relating to its speed) general walking speed has to be faster than 10ms (1/100!), so with "fast" subjects you need only a few milliseconds (1/500 and faster). So if you have a walking speed subject with moving clothes and the legs moving faster than the subject itself and add camera hand shakes, you fast end up at needing over 1/200.
Here you see a fast 28mm 1.8 lens outdoor with a fast subject 1/125 low ISO vs 1/600 high ISO:
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