just a feature request. Shipping cost if posted with another item

I know from the forum posts that you guys are working on shipping for future releases.

I think it would be a good feature to allow for someone buying a few items from the same store to have reduced shipping costs.

SO if the first item is a dvd for £5 and shipping is £1
if you add another dvd shipping in the UK will be about £1.20

At the moment if I add both items to the cart, the shipping will add up to £2.

So it would be useful to have another field for "shipped with another item cost" which is then defaulted to if there is already an item from the same seller in the cart?