This is a follow on from other threads: http://bitcointalk.org/index.php?topic=1994.0 and http://bitcointalk.org/index.php?topic=3441.0 and http://bitcointalk.org/index.php?topic=423.0

Specifically, I want to limit this discussion to the CURRENT implementation: no suggestions on how to make BitCoin better, no suggestions working around what might not even be a "problem". I just want to know:

In the current implementation, what are the circumstances that would need to be created that might leave someone out of pocket, if they accepted transactions without waiting for confirmation? Here's my understanding based on reading the other threads and the wiki, but if someone could confirm that would be great.

Attacker has some bitcoins, and is connected directly to the nodes of the eCommerce sites he's attacking, one in Chile and one in Mongolia. At almost exactly the same time, his modified client directly sends Transaction A to Chile node and Transaction B to Mongolia node, so each of those respective clients see the transaction as unconfirmed.

The two nodes start propagating, and we're now 100ms in. Because of normal lag and so on, transaction A propagates to 40% of the network, transaction B to 20% of the network, and no nodes have yet detected a double spend. At 110ms in, a node in Africa (which has already received transaction A) also receives transaction B, and considers it invalid, thus not propagating it. By 300ms in, every node has received both transactions but 70% of the nodes accepted transaction A (considering transaction B to be invalid) and 30% of the nodes accepted transaction B (considering transaction A to be invalid).

But both the Chile and the Mongolia nodes both say they have received the money.

After 15 minutes, a new block is generated within the 30% of the nodes thus including transaction B and excluding transaction A. The new block propagates around all the nodes, causing the Chile node to drop the received money transaction (this shows up in the client as something or does it just vanish?), while the Mongolia node carries on as if nothing had happened.

Is this how it works in the current implementation? For 15 minutes, or however long it takes for the next block to arrive, both eCommerce sites will think they've received the money?