Under normal circumstances, picking up, containing & disposing of the poop is no big deal.
When you're hiking, though, the options are few and none is ideal:
1) Let it drop and pretend you didn't see it. This is also referred to as "Not an option".
2) Pick it up, and leave the bag on the side of the trail with the intent of picking it up on the way back. Aside from the obvious fact that this only works for an out-and-back hike, it has got to get really old for people without dogs who are on the same trail. I wouldn't like to see someone's kid's discarded dirty diaper on the side of the trail, so why should someone have to look at my poop bag?
3) Pick it up, and put it inside of another bag, and then a ziplock bag, and then maybe another ziplock bag, and put it in your backpack, hopefully nowhere near your lunch. You spend the rest of the hike really, really, really hoping nothing else in your backpack pokes through the bags. Oh, and, despite the fact that you try to convince yourself it's not true, it still smells.
With these considerations in mind, I give you my most recent invention--
The Poop Jar
You'll need a Nalgene bottle.
I recommend the wide-mouth, unless you have a pocket dog.
You'll also need some duct tape & sharpies, since this is a "no going back" assignment for the bottle.
Next, make it pretty:
Let 'em poop, and pick it up. Into the Poop Jar it goes.
Depending on the size & shape of the deposit, a little manual manipulation squishing may be required to get it through the opening.
Do your best Ray Stantz and close the lid:
When the light is green, the trap is clean.
The Nalgene safely contains the poop and the stink. Additionally, due to its lightweight yet hard-shell construction, it is completely safe to toss into your backpack with no risk of squishing occurring.
The stink is so well contained that the Poop Jar can travel back with you in the car with no apparent odor.
In fact, as we discovered, it can sit in the house in your backpack that you forgot to unload, contained within The Jar, with no apparent odor (you may want to keep this part in mind, because when you do this, and you finally DO open the Jar, yeah, well, you can guess how good it is).
Penny says: You'll never guess what I'm carrying in MY backpack!
Happy (well-contained) trails to you!
Yours truly-
Tigerlily