Negative
No, I tried yesterday. You will have to pack and pay shipping back to Apple.
Nde is right. I just tried to return my iP4 (ordered online) at an Apple Retail Store. No dice. Apparently, Apple uses a different inventory system for Retail vs. Online -- but only for iPhones. This policy does not apply to Macs, iPods, and so on. I had to call Apple and set up my return. However, I do not believe you will have to pay for shipping. They said they were emailing me a shipping label, but maybe I misunderstood. Perhaps it's just an RMA label.
Their customer service may be better than others, but it certainly isn't anywhere near as painless as it was five years ago. Ah well. Call the 800 number on your invoice to arrange a return.