vCard Splitter used to be teh way to split up the huge vCard file that Apple Address book creates. But it doesn’t work under Snow Leopard, but I discovered this tip from Apple: To create multiple vCards at the same time, hold the Option key when dragging multiple cards out of the Address Book window.
To export all your contacts as separate vCards, select them all, hold down ‘Option’, and drag them to a folder in Finder. It would really help if this wasn’t the Desktop folder, unless you like major cleanups …