I know of someone who completely befuddled a sales assistant in Halfords by whipping out his iPhone3G and ordered his items for immediate collection and saved 50% by ordering online compared to the shop price.
I've used a PC connected to the Internet in a PC World store to order online and get my reservation number. It says you need to wait up to 2 hours, but that's really just to cover for unforeseen delays. In practice, give it a few minutes, take the item to the till and give the code for the discount.
I think eventually PC World and the like will have to offer online prices in store and acknowledge that while stores will run at a loss, given the overheads, it's important to have places for people to see things in the flesh. If the prices are competitive, you'd hope that someone might go away having seen various items and then order from that company online.
Those loss making stores might be generating sales that otherwise wouldn't exist, as I've seen things I wouldn't have ordinarily thought about buying, especially online with only a (often poor quality) photo for guidance.
I do think the click & collect idea is great, and I am sure Amazon will soon open stores to showcase its products. They'd be like regional distribution warehouses, with people given the option to walk away with products there and then or have them delivered the next day (as against collecting them, which Tesco seems to be going for with its new drive-through collection service).
Amazon even does evening deliveries, so imagine shopping at lunchtime at work and coming home to have it delivered!
If they don't do it, someone else will. But, Amazon seems to always be one step ahead.