Pentax, Olympus and Nikon all sell weatherproof dslr bodies and certain weatherproof lenses. That and reasonable precautions against very sloppy or dusty conditions and you'll be fine.

Truth be told I've never owned a waterproof camera, usually carry a camera and have never ruined one on the trail. I generally stow it when the weather is really miserable, which usually means I miss some good photo ops.

Keeping a big camera handy while hiking is a challenge. A lot of folks report good luck with a chest pack for their camera. I usually just sling it over my shoulder, but that's not ideal.

Cheers,