https://bitcointalksearch.org/topic/invoicespaymentsreceipts-proposal-discussion-128442
It probably isn't different. It's probably much the same. I am mostly identifying the problem rather than the solution, and it's entirely conceivable that I'm not the first.
Part of it is a social problem. People should be reluctant to send lots of BTC without a solid technological safeguard protecting them. Our community has not yet been stunned with the painful realization that big losses can and will occur as hackers intercept and manipulate communications. If Gavin's proposal is it, then I need to spend more time learning about it.