Do you have your own cup, container, etc?

It's quite common now to hear in a supermarket "do you have your own bags?". Is this the beginning of a trend? When will you go into Starbucks and they ask "do you have your own cup?", or go into McDonalds and they ask "do you have your own container?". Such a trend would no doubt be good for the environment (and no so good for the profitability of packing/container firms). It would also lead to a change in the pricing approach for some goods. For example, Starbucks might place your cup on the counter, and then weigh in the coffee. You pay per gram. The same might be true of a lunchtime takeaway place serving pasta salad.