From The Gap's perspective, this is a perfectly fine arrangement, with the chain getting systems that have proven to work under retail battlefield conditions, the ability to share in a little of the Apple buzz among its targeted younger demographic and likely attractive discounts given it is the first major chain to try it. (The fact that the boards of both Apple and The Gap have execs from each other doesn't hurt with those price negotiations, either.)
The real question, though, is not whether this move makes sense for The Gap, but whether it's something that other chains should now seriously consider. There are plenty of mobile applications—and far more developers eager for work—that can deliver similar if not identical functionality. Will the convenience of using Apple's devices make that the way to go?
Unlikely, given Apple's history of charging a strong premium for its brand. After a few months, consumers are not likely to care what make your mobile POS units are. How many of your regular customers could even name the POS brand you're using today? With no ongoing customer draw, it's unlikely Apple would be able to deliver enough value to match its pricing.
Another consideration: Historically, companies view the new technology as slightly different versions of the old technology. Don't think of mobile payment merely as a way to make POS machines small enough to fit in an associate's pocket. Differentiate as much as possible.
Why not use the units to interact with CRM and loyalty cards, via either a swipe or interacting with an RFID tag? These abilities would now help the associate make sales rather than only tendering them.
As an associate talks with a customer, not only could that associate glance at purchase and browsing history of that customer, but the associate could take notes from the customer conversation. Those notes could be added into the CRM file, accessible to another associate a week later—or, for that matter, to a call center representative or even software behind your Web site.
Mobile payment has the potential to be the greatest retail advance since the Web. Connecting with an established proprietary player such as Apple could prove dangerously limiting. That's fine for small retailers, and that market could be highly profitable. But for major chains, it is likely not the optimal choice.