Ricoh just announced a new camera model (G600) that has specs as close to ideal for backpacking as I have found.

Here are the major specs. I will comment on why I think these are ideal below:
1) Waterproof, dust-proof, shock resistant to military & JIS standards, and large buttons for use with gloves.
2) Compact point-and shoot fits in pocket, with no protruding lens, even during zoom.
3) 28-140mm equivalent wide-angle zoom.
4) Lithium-Ion rechargeable battery can be replaced with 2 AAA batteries.
5) 37mm filters can be attached (allows for polarizing/ND filters as well as optional 22mm Wide Angle)
6) Up to 3200 ISO allows for low light shooting (though probably very noisy; it is a point-and-shoot after all)
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Re: 1) This is really cool; it can be dropped from 5 feet, it is rain-proof and waterproof to 1m, it is dust-proof. These are huge deals, as I don't think the Pentax waterproof cameras are dust and shock proof.
Re: 2) This camera will fit into pants pocket or a hipbelt pocket. Anything big enough that it has to be stowed in my backpack I find I don't use. It also includes a lanyard for wrapping around your neck and stowing in your shirt pocket.
Re: 3) This is also really cool; for me 28mm wide is absolutely essential for outdoors. I used to carry around a huge super-zoom camera for backpacking, but it started at 36mm. 90% of the time I found I wished I could go wider. If you haven't tried a 28mm outdoors, trust me; it's essential. It gives me so much more foreground, and I can capture the whole mountain, not just the middle of it. It also allows me or my hiking parters to be on the side of the picture, not blocking the scenery but still visible. The 140mm is plenty long enough for most zoom needs, unless you plan to take close-ups of animals (but for that, you'd probably want a good DSLR; even with optical image stabilization on my old super-zoom, most of my animal shots were somewhat blurry).
Re: 4) This was the real surprise for me. It's hard to find a decent AAA battery camera, let alone a AA camera, especially a WP one. It's a great compromise; they include a powerful rechargeable battery, but it can be replaced with AAA if you run out of juice or are on a thru-hike. Now I only need to carry one type of battery for my Camera, GPS, and headlamp. Way, way cool.
Re: 5) Again, this is sooo cool. I can start using a polarizing filter again, and even a sun visor thingy (whatever they are called), which is helpful for wide angle cameras, which capture more of the sky and are more prone to lens flare. This was the thing I missed the most when switching from my old super-zoom to my current point-and-shoot.
6) We'll have to see about how noisy this camera is, but it's nice to know it offers high ISO settings for low light. Ricoh is a well-respected camera company amongst enthusiasts. Check out http://www.dpreview.com, a highly respected camera review website, for reviews of their other camera models.
The only major downsides are the poor video mode (640×480) that only lasts for 21 seconds, and Ricoh is not easy to find in the US, so it'll likely be an internet purchase. They are really behind the times with the video mode, but it should suffice for short comments or a quick pan of the scenery. It also doesn't offer 16:9 mode, which I really like in my Panasonic (but you can crop these later, though that sounds tedious). It's also likely to be more expenive than average P&Ss, and it weighs 9oz (not bad at all, though, considering it is ruggedized). And of course, all the downsides inherent in point-and-shoot cameras. But for a lightweight, pocketable camera, I think this will be pretty hard to beat.
I know that if I was attempting a thru-hike, this would be on my short list of choices (pending a good review of the camera after it comes out in May).