After posting that, I waited all day Saturday (until 9 PM Eastern time, which is when all the folks at Apple go home) for the RMA and mailing label. Didn't get one. Ditto Sunday and Monday. On Tuesday, I call Apple, tell them that I was told that I could expect a link to a mailing label sometime Saturday afternoon, here it was Tuesday morning and still hadn't gotten it. They pass me on to someone else, who explains that it takes 48-72 hours to issue an RMA. I ask the young lady why this wasn't explained to me on Saturday, when someone told me that I could expect the RMA by the end of the day. She, of course, had no explanation, but did say that she would expedite the RMA process, and once FedEx let them know that the computer was on its way back to them, they would build me a new system and have it on its way by the end of the week. An hour later Apple issued the RMA, linked me to my mailing label and apologized for any confusion. I dutifully boxed up the computer in the original carton, sealed it with tape, affixed the label I received to the box, and brought everything to the local FedEx drop point. It was on its way by Wednesday afternoon.
I got another email from Apple, highly apologetic, informing me that my new system would be on its way by Friday ("on or before January 5"), and I should expect it by the early part of next week. This morning, I get another email from them, explaining that they've had "an unexpected delay" and that I should now expect it no later than the first part of the week after next.
So, that's where it stands, other than to say that if this computer is DOA, I'm buying another Windows box and the hell with them.