Answer: no one. In Phoenix, it's not much of an issue, but in places with actual weather and water that falls out of the sky, well, something's gotta give.
And now a well-timed word from our sponsors:
For a limited time you can get a free eyepiece with Think Tank Photo’s Think Tank Photo’s Hydrophobia rain covers. The Hydrophobia 70-200 and Hydrophobia 70-200 Flash rain covers accommodate a DSLR with up to a 70-200 lens and, in the latter, a flash. The Hydrophobia 300-600 rain cover protects a DSLR with a super telephoto lens (300 f2.8 up to a 600 f4) attached, with the lens hood in position. These heavy-duty rain covers provide protection during even the toughest downpours, wind storms, or other challenging conditions. What's more, you can actually attach your DSLR and simply carry it by the rain cover. The sleeves are big enough to not only let you control the camera (with the help of a clear window around back), but swap out batteries or memory cards as well. When you check out of the shopping cart you will be asked which eyepiece you would like to receive for free.