Thanks for the comments, everyone. Things finally did get straightened out, but I've been busy all weekend and wasn't able to post until now.
I finally got my computer. The UPS driver delivered it to the registries office a block away; I live in Edmonton where most of the street addresses are numbers (137 Ave, 62 St and so on), and the registries office's address is very similar to mine (same 'house' number, but they're on 82 St, and I'm on 83 St.)
According to the driver, UPS did call him to ask about the delivery, and he went back to pick it up, and then delivered it to me. He also apologized profusely. I then called Apple back to let them know I received it, and to cancel the investigation (talked to a different lady and she was also great; Apple's customer service was stellar at all times; you could tell they gave a shit).
I'm still filing a complaint with UPS, though, because their CSR was absolutely useless. She was able to contact the driver, but told me she couldn't. I understand that they're supposed to stick to a script, but common sense should have also come into play (i.e. "I've already read this one line twelve times, I think the customer might be tired of hearing it.") The typed version of my post didn't really convey the fury I was feeling when I was talking to her, but I'm sure she was aware how pissed off I was, because it was obvious in my tone of voice (I was on the verge of swearing at her, but she could've just said I was being abusive and hung up on me). And, there should have been an apology, but I never got one from her.
I think it was a case of the CSR thinking, "I don't feel like dealing with this shit, so I'll just repeat the same thing over and over again until the customer gives up."
She didn't explain why she couldn't contact the driver (and that, in itself, was a lie), she didn't listen when I told her that the package had been delivered to the wrong location, she didn't explain why I had to contact Apple to start the investigation (after everyone here explained it, it finally made sense to me, but why didn't SHE explain that?), and although she repeated endlessly that she wanted to help, she was no help whatsoever.
So, I was relieved to get the computer, but there was no reason for her to just brush me off like that and give me the runaround.
I'm also thinking that, even if I file a complaint, nothing will be done. If UPS is that bad, they probably have hundreds of complaints coming in on a daily basis, and I'd be just one more small voice in the crowd. I'm starting to think they're the Comcast of the delivery world. But, I guess if there are enough voices, something might be done.
At least the driver apologized, and he was really nice.