By far, the biggest concern for a waterfowl hunter with a camera in the blind is the weather and the surrounding elements.
This assumption goes hand in hand with the notion that typically, the worse the weather, the better the hunting. Rain, snow, sleet, water, and extreme temperatures are all among the worst enemies of a digital camera, and managing to take photographs in these environments is risky at best. You can take plenty of precautions but you'll likely never be completely satisfied with your measures and will at some point experience some roadblocks. It's just the nature of the beast.
The extent of these roadblocks can vary from very minor, to catastrophic. Minor problems could include dead batteries, fog on the lens front, or a bit of fogging on the LCD viewing screen. Major problems could consist of submersion of a camera, freezing of the info screen, or moisture between the elements of a lens.
All of the latter problems will likely force you to replace the damaged item, leaving you with an expensive heartache. The cost for a top of the line camera body alone can run upwards of $4,500. Any trip to the camera shop will automatically start at a couple hundred dollars.
Minor problems are relatively easy to prevent when you prepare your gear for the hunt. Since the inevitable cold weather will potentially sap a camera battery in no time; it is imperative to have a back-up battery, or set of batteries if your camera does not take rechargeables. This could save the day. Keeping the battery pack out of the camera and close to your body can stave off the effects of the cold indefinitely. The closer to the body, the better. Remember to keep your extra set of batteries close to the body as well. Although not as dramatic, the frigid temps will also drain new batteries.
Keeping your camera in a well padded camera bag, or a floating blind bag with compartment dividers will keep your camera gear fairly dry and protected from bumps and jarring. Having the lens off the camera body will also lessen the chances of damage occurring to your gear from a jolt. Be sure to keep the body and lens caps on each piece. For a little extra safety, place the gear into zip lock style bags to keep out even more moisture and dirt.
Don't forget to keep your flash and memory cards protected as well. Also, never leave your camera lying unattended in the blind. I guarantee you that it will either get knocked to the floor, pushed into the water, or a dog will shake its self dry directly over the top of it.