This new General Store is purchasable from the Market for 20 Wine Cash. Once you purchase a store, you can then click on it to begin pricing items in your store as you wish. You can sell items for coins or Wine Cash, and My Vineyard will take a 10% cut (or a minimum of 1 WC or 100 coins). At any time, you can click on the shopping bag icon on the left side of your screen to see a list of stores that you can visit, and you can click on them to go shopping.
Shopping is done by visiting friend's vineyards with stores, and clicking the shopping cart at the bottom of the game. Any item that is for sale will then have a price tag on it so that you can click on it and buy it directly from that store. The difference between this, and say, PetVille, is that when you buy the item it will actually leave your friend's vineyard and go to yours. The seller will also get the profit. This is a really neat way for players to get rid of old premium items that they no longer want, and for newer players to have access to items that are no longer available for purchase in the game.
Player can also pay 1 Wine Cash to have their store listed in the Featured List so that more players will see their store. This means that players who aren't neighbors can still see the stores and go shopping. When you're visiting a friend's vineyard, you will see other players there and you can actually chat with them, which is a feature of My Vineyard.
Playdom's My Vineyard definitely takes social to the next level with the ability to shop in a multiplayer space with other players, and buy and sell virtual goods from each other.