I wish I could say that this was unbelievable, but you know... it really isn't. Disappointing and aggravating, but not actually surprising.
I'm really starting to lose all faith and respect in the local UPS people. At my mom's house and the duplex I lived in before they'd often just not deliver packages on Fridays (their normal delivery time the rest of the week was around 5-6pm so I guess they just wanted to get off early on Fridays), and here, I've had packages show up as "delivered" only to have them appear at my door a week or two after the system said that they were "delivered"
Really not impressive at all.
Surprisingly, the US postal service seems to do a lot better and they're a lot cheaper.
The only upside to this is that a) the package wasn't critical (but I was still looking forward to getting it) and b) I should be able to get a refund on the shipping charges... hopefully once the package is found.