They politely circled the "TO" address this time, but evidentally that was the extent of their involvement--actually delivering it to said address is way beyond the scope of the US postal service.
I have double and triple checked, and there is nothing that should render it undeliverable--it's clear, legible, and complete. They just keep sending it to the "From" address. Despite the big label saying "FROM" in all caps. And the handy circling.
If this wasn't something that I'd, y'know, been paid for and all, I'd write "Return to Sender" on it in the spirit of experimentation and see if it got home that way. But no--somewhere, a nice man is waiting for his art, and thus, I must go to the post office tomorrow and scream a lot.