Nintendo just announced a partnership with Best Buy to have demos from the E3 show floor available in store. It's not quite what I was suggesting, but I could totally see it evolving. Imagine bringing your 3DS into the store for some special E3 street passing and little digital goodies, like demos and maybe even free limited edition virtual console games.
Thinking about those party bags, it would be amazing if they gave out some E3-style swag to, say, the first 100 people.