Hugh McLeod of gapingvoid.com nails it with his latest post: when selling a physical object (e.g. your wine) in a virtual setting, it's good to have proof that other people have already bought it.
Twisted Oak does this well, with pictures of happy customers and rubber chickens, "proving" that drinking Twisted Oak is fun. Contests, as Twisted Oak has shown, are a great way to get people to submit pictures. Maybe we're all lemmings, but that doesn't negate the value of showing people engaged with your product.
Anyone else out there actively inviting their fans to submit pictures involving their wine (or chickens)?