Harold McGee writes in the NY Times about gelatin filtration:

— a way to make sparklingly clear liquids that are intensely flavored with … well, whatever you like: meats, fruits, vegetables, cheeses, breads, any and all combinations of ingredients.

Why would anyone want to make such a thing? Think of such liquids as essences. They have no fibers, no pulp, no fat, no substance at all. They're just flavor in fluid form, perhaps with a tinge of color, like a classic beef consommé. In fact chefs are calling these essences consommés, and they often use them the same way, as a soup or a sauce. And they can be delightfully surprising, because their appearance often gives no hint of the pleasure they're about to deliver.