An anonymous network for shipping physical items is theoretically possible, and could be organized like Tor.
1) When you buy something you give the seller an encrypted version of your address that s/he cannot read.
2) The seller ships the package to a reshipper who has the ability to decrypt your address.
3) The reshipper then ships your package through normal channels like UPS.
The main benefit of this system is if the seller is busted for some reason, your name/address are not compromised.
An obvious weakness of this system is if the reshipper is compromised. A way around this is to have multiple reshippers with layers of encryption and each reshipper peels off only one layer to see which reshipper to send it next (or to you).
You the buyer could even encrypt the entire reshipping route to follow. The seller would then ship the package to the reshipper you specify when s/he decrypts the address.
The main weakness of this whole deal is the "exit node" i.e. reshippers that can see your real physical address so it can be shipped conventionally to you.
Interesting concept. In theory, the "exit node" could simply be a drop location, although this could still be subject to surveillance.