I'm not sure how I feel about centrepieces. Whilst they can be beautiful and I also think they cause couples quite a bit of grief (and expense) trying to pick the right ones.
So I like the nice cheap and effective idea of using wine bottles. Now this image from Martha Stewart Weddings uses the wine bottle as table numbers but I see no reason why they can't serve as centrepieces. You could be more creative with the label if you wanted and pair up with tea lights around the base of each bottle for a lovely warm glow if you wanted to make more of it. And you can allow guests to drink the wine in the bottle making for a centrepiece guests will actually get use out of!