Bitcoin is issued in decentralized manner, however the quantity of BTC is fixed, we can say that the money supply quantity of BTC is determined centrally. However, when BitUSD is created via selling short, how much BitUSD exist in the market depend on the finished short selling quantity. What we can expect is that when the demand to BitUSD arise, more BitUSD will be created by the selling short transaction. And when the demand to BitUSD drop,more BiUSD will be repurchased to cover the short position and then the total quantity of BitUSD will drop. In this sense we can say that the supply quantity of BitUSD is determined in a decentralized manner.this is a new property of cypto-currency that brought by Bitshares.

Not sure whether the designers of Bitshares are aware of this, but seems this is really the case.

sending 0288d26b3a4e44dbda19029d4dca8f13781e721fcb0b17820ce4a32ff7184f8e
sending 036320273899ed83f57ac064d1203877c67c6b03baa9f6f49c8ad33b3a35cd0d
sending 0198afd1d6709af1fc3d4c162cd248d88abd33bfa9f4f156c06f49995bfa6b18
sending 026bf1db76ec79f5681777214499f98170b936c3cf1c05a3cf8cc879e938bd3b

valid: 7  invalid: 3  balance: 0.278396  paid: 0  pps: 0.0397708  address: PYFVMWv3rKYvsNgyu8YjHmEruskZtTUxWe  hpm: 21.9675

saw this but no income to the address, under minimum threshold?

官方论坛建立之前，很多中文介绍文章都发在巴比特论坛的Bitshares板块，可以参考：
http://8btc.com/forum-66-1.html