Salt is an ore found underground in large veins or on the seabed (game logic)
It can be used to cure raw meats. When cured raw meat is cooked, it is much better. It is also an ingredient for salted butter.
Salt can be made onto salt blocks. It is used for decoration, or to store large amounts of salt. It dissolves if 10 blocks below the ocean surface. Also, it stops ice from forming nearby.
This is a pretty cool idea, I'm all for having more items in the base game.
I gotta say though, the first thought that came to mind when I read your post was, is this some April Fool's Update Minecraft is planning called The Salt and Pepper Update