Also known as Ground Cherries or Cape Gooseberry. See the Physalis peruviana picture at Wikipedia. I ate some of these fruit when I was in Germany last summer and I liked it. Prior to that trip I hadn't even heard of it, let alone tasted one. The proprietor of the restaurant where I had them knew them only as Physalis - no common or species name. He was surprised to learn the English common names.
Last night I ran across mention of them in the May 2008 issue of Organic Gardening which I picked up at the YMCA book exchange. They are seed-propagated and, like tomatillos, they have a papery husk. Stored in the husk in a container that allows transpiration they are supposed to be good for up to 3 months at 50 F. They get their common name of Ground Cherries because they drop to the ground before they ripen. Thereafter, storage at room temperature for a week or less will ripen them.
Because they are in the tomato / tomatillo family they have the same disease susceptibilities so if I were to plant some next year I'd have to not use my normal garden area.