There have also been some changes in grocery shopping recently. Publix had a program where you ordered online and delivered your groceries. It tuned out to be ahead of its time and not cost effective for most, but it did provide a different way of doing things. I see a possible variation on this -- maybe buying online and then doing the pickup yourself? ...but I don't see things laid on on big aisles in a traditional way forever. As our population grows, that experience is going to become unmanageable to do manually.
Grocery stores in my area have done the delivery thing for several years now. I remember we used the service once, right after Josh was born, and he's 5 1/2 now. We ordered and paid online with a credit card, and they delievered it a few hours later. The drawback was that if they were sold out of an item you wanted (for example Skippy Peanut Butter), they'd substitute a different brand (for example JIF), and sometimes you may have wanted the specific brand (I am partial to Skippy). They give you the ability to say no when the guy delivers the substitute, but then you need to wait for them to issue you a credit.
They also do have the option of shopping online and then picking it up at the store. This works really well with working couples, who stop to pick up their groceries on the way home.
For both of these services, they have a service fee (something like $10 for every hundred you spend, with a $10 fee if you spend less than $100). The drawback for retailers is that you lose out on a lot of impulse sales, which is really big in grocery stores (people shopping hungry tend to buy more foods they didn't plan to buy).