The idea works for me, too, and I think it could be expanded to any PC device with USB or wireless connectivity.
Brought into the store, your PC device could connect with the store's LAN the same way you might in a Starbucks. Then you browse the catalogs, find the book you want, purchase through your device, and download the e-book. If you have your own device, all you need is a place to sit and browse. If you don't have a device of your own, you can use a kiosk and either have the e-book e-mailed to you, or dispensed on a memory card that you input (or purchase on the spot).
Now, if only we could raise the few million dollars we'd need to put up the first prototype store...
