Although I'd love to take an SLR with a range of lenses, flash, filters, and tripod, it wouldn't really work with my style of hiking. Aside from the weight and bulk, if I have to spend 10 minutes setting up a photo, I probably won't bother to stop. On the other hand, if I have a camera in my pocket ready to go, I'll probably end up with a decent amount of good quality photos.
With the decision made to bring a small and portable, rather than large professional quality camera, there's still a number of other options - but the largest one is probably film vs. digital.
Film cameras, although becoming obsolete for anyone other than a traditionalist or specialist, do offer some benefits over digital. Weight, price, and durability to name three. A moderate quality, feature sparse film camera can be had for under $50, weighs a couple of ounces, and can survive most punishment you throw at it. A lot of them don't need batteries unless you want to use the flash, offering further weight savings (not to mention 6 months on a thru-hike without having to recharge). On the downside, you have to buy film, carry plenty of it, and pay to have it developed.
Digital cameras are generally heavier than film cameras, there's no getting around that. Up until now, I usually carried a Kodak EasyShare DX4900, at nearly 10 oz. including battery, memory card, and wrist strap. Although I've had excellent results, often comparable to pictures taken with much higher end cameras, I had to keep it in a padded case, waterproof bag, and be extremely careful around sand and wet areas. It is also fairly bulky, and feels uncomfortable in a pocket. The advantages of a digital camera, including holding hundreds of photos, still made it worth it to me over a film camera.
Last week, I decided it was time to replace the aging Kodak with something more suited to the outdoors. I did quite a lot of research online, and narrowed it down to either the Olympus Stylus 850 SW or the Pentax Optio W30. Both cameras came in at roughly the same price, and had a pretty similar feature set. Both are water and dust proof, lightweight (around 5 oz inclusive), and small enough to fit in a pocket.
I went into my local camera store and asked the clerk to help me narrow down my selection to one camera. He suggested that the Olympus had one major advantage: it was shock proof as well as waterproof. Knowing how rough I can be on gear in the outdoors, this sounded like a great feature. I paid the man, came home, and crossed another 5 oz. off my gear list!
In two weeks I head off for a section hike of the Pacific Crest Trail, so I'll be sure to post some photos and a review of the camera when I return.