I've used a Pentax Optio for the past 2 years while backpacking and found no need provide any special protection for the lens. I am now carrying it in a hip belt pocket and so far so good!
I do have the protective skin around the body of the camera which makes the lens slighty recessed. I tend to worry more about the LCD screen on the back of the camera but after 3 week long BP trips and several weekend trips not to mention paddling on numerous rivers and a few bicycle trips, its holding up great.