Well, what do you know. I stopped in Wal-Mart on the way home the other night for some oil, and I took a path through the Food aisle, and there I saw Star-Kist tuna in foil packaging - much like an MRE.
http://www.starkist.com/products/Expiration date was Novmber 2008 - not as long as a "real" MRE, but certainly enough to keep a few in my car and computer bag.
In sniffing around the food aisle, and inspecting expiration dates, I found quite a range of longer-life non-canned products on the shelf, including not only the Tuna, but also a variety of dried foods, which are less useful in an emergency, but still not a bad thing to pack.
As a test I ate the tuna for lunch today, and I'll pronounce the water-packed better tasting, and the sunflower-oil packed a better "energy" food (more fat) but, to me at least, not as tasty.
I've been looking more closely at the expiration dates. With high-temperature treatment and cobalt irradiation, it seems that many of these "to-go" foods can be packed for 2 or more years, no problem.