I have obtained the mms on the m8a1 in my last game and scanned all of the traincars i could find... i found nothing.. from the outside.. if you think about it the only way to can see things through the walls with the mms is the enemy that is movies.. (zombies or denizens) i also used it to look in thick grass under the semis and other obstacles. i was unable to finish my scanning because zombies + lava don't mix. the places i was able to scan was the cabin, power station, corn field, farm, train cars, and along the sides in the fog in-between them. places i missed was town, bus depot, diner, nacht, and bridge.
One of the things that intrigued me about the poem was saying that we run over it all the time and don't notice.. well if you look at the cracks on the ground outside the cabin it looks like they say "252" i don't know if that has any significance or not.
If your in theater mode you can fly through the hole in the roof at the cabin and be on top of the cabin. this is the only time I've seen where you can go somewhere with a camera that the player cannot (except for camera mode glitching out side of the map).
So if someone wants to continue the scanning in the places i missed, feel free and keep us informed. Or if anyone has any thoughts on the writing at the cabin post them.