I'm curious about the mechanics of doing such a transaction safely.
phil is often used for escrow
Escrow makes sense, but using poor Phil as the escrow agent sounds awfully burdensome for him!
My Escrow Dapp is the perfect solution: http://escrowmyether.com/
When the buyer confirms he received his goods (in this case, once USD or other coins reached his address/account), he can automatically release funds (ETH) in the Dapp. He can also initiate the transaction in the Dapp. All these can be down without going through the escrow agent, just put escrow agent's address in the correct field. The escrow agent only needs to be involved when a dispute occurs.
I escrowed for 9.74eth so far and only one of the transactions required my intervention. All other transactions were initiated and fund released without me taking any action.
If you'd like, you can use my address , details in sig. Also, anyone can be an escrow agent on the platform, just update your name and fee and advertise your service.