I am wondering what inventives do various Crypto 2.0 systems provide for IOU Gateways (ones that create currencies backed by other currencies or commodities, like USD, BTC or the like)?

Just to be clear, by "Gateway" I mean a business that takes currency external of the Crypto 2.0 system, issues IOUs in the system for that currency and is responsible for converting the IOUs back to that currency. For example, Bitstamp is a Gateway for USD and BTC in Ripple. By "IOU" I mean a token in the Crypto 2.0 system that can be created easily and is not native to the system (for example, USD and BTC in Ripple are IOUs, XRP is not. BTC is not an IOU in the Bitcoin network).