Reading this thread (just reading it, not participating in the experiment!) has finally made me understand how Ripple works. There were many threads that tried to explain Ripple, somehow I just did not get it because nobody could really explain to me exactly how the ownership of value (or the promise of such) propagates from A over B to C in Ripple and what it all means and its implications, now after reading this thread I finally understand. This thread is highly educational! Especially the explanation what happened to web3er's ฿10.15/Bitstamp finally made it all clear to me! Thank you!
It's simple really.
TradeFortress promised to pay each user 1 BTC who trusted him 100 BTC.
He sent IOUs for 1 BTC to each person who trusted him.
He had no BTC.
As soon as somebody who had trusted him had BTC backed by a gateway that was trustworthy, some of those promises has a trust chain back to a source which would turn the IOUs in to Blockchain BTC.
TradeFortress did not issue some kind of different, made up, BTC, he promised to pay people real BTC, sending them IOUs.
I trusted him, using an account with trusted BTC IOUs in it, and people then cashed out the BTC HE (TradeFortress) owed them.
So, TradeFortress owes me 10.15 BTC, nobody owes him any.
He also has many BTC promises ready to be cashed in, 455+ BTC by his own count, which can be cashed in the second anybody puts trusted btc IOUs from a reputable gateway in to any of those accounts.
The ripple system worked perfectly, and had already been demonstrated and used for months.
TradeFortress simply demonstrated it again, but in a very untrustworthy way, not fullfiling any of his promises. Simply, he only demonstrated that he is untrustworthy, and indeed that he doesn't pay back money he owes.