ARS Technica has published a guide about I/O virtualization, you can check it out over here.
Even though it has been used pervasively in datacenters for the past few years, virtualization isn't standing still. Rather, the technology is still evolving, and with the launch of I/O virtualization support from Intel and AMD it's poised to reach new levels of performance and flexibility. Our past virtualization coverage looked at the basics of what virtualization is, and how processors are virtualized. The current installment will take a close look at how I/O virtualization is used to boost the performance of individual servers by better virtualizing parts of the machine besides the CPU..